Voters are determining whether the next president enters office with a friendly Congress or a hostile one set on blocking their policies and nominees — and as the election roars into its last moments, it’s still very unclear what the makeup of the House and Senate might be.

Most House races are not competitive. But House leaders are closely watching about two dozen toss-up contests to see whether Democrats or Republicans end up with the 218 lawmakers needed to control the speaker’s gavel, the agenda and the floor schedule.

The GOP’s razor-thin majority during the past two years created significant obstacles for leadership’s legislative goals and ended Kevin McCarthy’s speakership.

Neither political party is expected to gain a large House majority during the next Congress, which begins in January. There’s even a possibility the majority party has less wiggle room than the 220-212 split that currently exists, along with three vacancies. Experts warn it may not be known on election night or for some time who’s won the House.

Senate leaders have been equally focused on hard-fought and close campaigns in Arizona, Michigan, Montana, Nevada, Ohio, Pennsylvania and Wisconsin. Any one of them could deliver control of the upper chamber.

Republicans are favored to turn over the West Virginia seat occupied by Joe Manchin III, potentially pushing them past the 50-member benchmark if they hold onto seats occupied by incumbents Ted Cruz in Texas, Deb Fischer in Nebraska and Rick Scott in Florida.

If Democrats keep 50 seats, that would mean whichever party holds the vice presidency controls the Senate, making even just one pickup in either direction a priority for both political parties.

The outcome in both the House and Senate will have sweeping implications for the country’s future, including whether the GOP overhauls the Affordable Care Act, a.k.a. “Obamacare,” how lawmakers address core aspects of Republicans’ 2017 tax law set to expire in the coming months and whether the country defaults on its debts for the first time in history.

Four tense toss-ups in the Senate

The nonpartisan Cook Political Report with Amy Walter rates four Senate races as toss-ups.

While the campaigns have shifted a bit during the past few months, Michigan, Ohio, Pennsylvania and Wisconsin are all considered neck-and-neck heading into Election Day.

Arizona and Nevada are categorized as leaning toward Democrats, and Montana is expected to lean toward a Republican pickup, potentially giving the GOP its 51st seat and a narrow majority.

The battle for the Senate fundamentally ends where the cycle began.

It’s also possible there could be upsets in Republican-held states traditionally considered safer, like Florida, Nebraska and Texas. That could alter the math for both Democrats and Republicans, depending on how things shake out after all the votes are counted, recounts finalized and lawsuits settled in the following days and weeks.

Jessica Taylor, editor for U.S. Senate and Governors at the Cook Political Report, said in a statement released Friday the “battle for the Senate fundamentally ends where the cycle began — with an overwhelmingly favorable map that very likely portends a GOP majority.”

Her projections show the GOP picking up two to five seats, giving the party a majority between 51 and 54 members.

A narrower majority, Taylor said, would allow “moderates like Alaska Sen. Lisa Murkowski and Maine Sen. Susan Collins to wield outsized influence in the next Congress.”

Will some voters split their tickets?

Michigan Sen. Gary Peters, chairman of the Democratic Senatorial Campaign Committee, said during an interview with Washington Post Live in late October that he expects voters in Montana and Ohio will split their tickets.

He acknowledged getting voters who are likely to support Republican presidential nominee Donald Trump to also support Democratic senators Jon Tester in Montana and Sherrod Brown in Ohio will be much more challenging than in the past.

“Certainly, it’s not easy if there’s a lot of political gravity,” Peters said. “I’m not going to sugarcoat that in any way.”

But, he said, both Tester and Brown have been consistently polling within the margin of error against their GOP challengers.

“It’s about who’s going to get their voters out and do the kind of ground campaign necessary to win,” Peters said. “We’re doing that in Montana. We’re doing that in Ohio, as well.”

The Senate is more important to the next president than the House, since the upper chamber is responsible for vetting and confirming the next commander-in-chief’s selections to the Cabinet and judicial nominees.

The Senate is the more bipartisan of the two chambers, thanks to the legislative filibuster — the rule requiring at least 60 senators agree to advance legislation toward final passage.

Without bipartisan support, bills and some nominees will be stuck in limbo, regardless of which party runs the Senate or controls the White House.

Possible standoff

Philip Wallach, senior fellow at the American Enterprise Institute, a conservative-leaning think tank, said a Kamala Harris administration and a Republican Senate would need to work out an agreement quickly “or risk going into some kind of protracted standoff over executive branch nominations.”

Both Trump and President Joe Biden had the luxury of same-party Senate control during their full terms, and former President Barack Obama had a Democratic Senate during his first six years in office. The prospect of Harris having to work with the opposing party to establish her Cabinet would be especially challenging, Wallach said.

“I would expect Republicans to try to come up with some pretty concrete asks as a conference: To say, ‘If we’re going to put any of your nominees up for a vote, here’s what we want in return, and here’s what kind of nominees we will accept.’ And, you know, I expect that would play out as a fairly heated public confrontation,” he said.

Trump and a Republican Senate would likely agree on some nominees and policy goals, though there would be significant differences over issues like tariffs.

“I think there are a lot of Republican senators who want to see some real limits to that, who still think of themselves as basically in favor of free trade and making sure that American businesses don’t find themselves on the wrong end of a trade war,” Wallach said. “Especially in the Senate, I just don’t think they’re that eager to just march to Trump’s tune.”

A Trump administration, he said, could also disagree with GOP lawmakers on the specific details of how to address tax policy.

“I think it’s a very live possibility that there could be a much more confrontational kind of dynamic this time around, in part because Trump and some of the people right around him have this idea that playing nicely in 2017 was a big mistake,” Wallach said.

House ‘as close as it’s ever been’

Control of the 435-member House is more uncertain than the Senate, with 22 races rated as toss-ups by the Cook Political Report.

Twelve of those are held by Republicans, while 10 are occupied by Democrats. At the moment, 205 House seats are at least leaning toward a Democratic win, with 208 districts at least leaning toward Republicans.

The Cook Political Report’s final projections range from Republicans adding five seats to their majority to Democrats picking up 10 seats and taking over the majority.

“The race for control of the U.S. House remains as close as it’s ever been,” Erin Covey, editor for the House at CPR, said in a written statement.

“The battleground is confined to a few dozen seats, with neither party having a clear advantage in a majority of seats,” Covey added. “And with several competitive races in West Coast states that take longer to count their ballots, it’s highly possible we won’t know which party has control on election night.”

The House doesn’t have any role in confirming presidential nominees, but is essential in turning bills into law. And unlike the Senate, there’s no legislative filibuster, which means the majority party can approve any bills it wants without buy-in from the minority party, as long as the leaders in the majority have the votes from its members.

A divided government is unlikely to produce sweeping changes.

Republican control of at least one chamber of Congress and a Harris victory would force significant bipartisan compromise on must-pass legislation, like the dozen annual government funding bills and the defense policy bill known as the National Defense Authorization Act.

It could also lead to the types of bipartisan legislation that Biden made a hallmark of his term in office, including the infrastructure law.

That type of divided government is unlikely to produce the sweeping changes to home ownership, prescription drug prices, price gouging and reproductive rights that Harris has highlighted throughout her campaign.

But it could lead Republicans and Democrats to resurrect the bipartisan immigration and border security bill that Sen. James Lankford, R-Okla.; Sen. Chris Murphy, D-Conn; and Sen. Kyrsten Sinema, I-Ariz.; agreed to this year.

Trump in the White House and Democrats holding onto at least one chamber in Congress could also force bipartisan compromise, though probably with a far different tone and approach than under a Harris-Republican Congress scenario.

GOP trifecta?

Trump regaining the presidency along with GOP control of Congress would give the party at least two chances to use the complex budget reconciliation process to pass certain legislation.

The party would probably use one of those opportunities to address provisions in the 2017 Republican tax law that have expired or are about to.

The budget reconciliation process, which has considerable rules and restrictions, is how Republicans passed the tax bill during Trump’s first term in office.

It doesn’t require at least 60 senators to advance the bill. But it does include something known as a vote-a-rama, where the Senate holds dozens of votes on amendments to the bill. The process typically lasts throughout the night and gives the minority party a chance to force their colleagues across the aisle to vote on tough issues.

Budget reconciliation is the process Republicans used to try to repeal and replace the 2010 Affordable Care Act during Trump’s first term in office.

Speaker Mike Johnson, R-La., said in late October on Fox Business that some of his prior comments about overhauling the ACA were taken out of context and that he wants to make changes to the program, but not end it.

“I said the ACA, unfortunately, is deeply ingrained in our health care system now,” he said. “Do we need further improvements? Absolutely. We need to expand quality of care, access to care and obviously lower the cost of health care.”

Johnson said during the interview that he was “convinced” Republicans would gain unified control of government following the election and that he had compiled a “two-hour slide show presentation” detailing what the GOP would do with that power.

“We will secure the border on Day One with a President Trump executive order and then legislation to follow, and we will turn immediately to the economy,” Johnson said. “Energy policy will be the center of that, as well.”

Deeply conservative House bills might not garner the support needed to overcome the Senate’s legislative filibuster.

Unified Republican control of Congress and the White House would challenge the GOP to address the nation’s debt limit mostly on its own during the first half of next year after the current law expires.

A default on the nation’s debt is vastly different from a partial government shutdown, which takes place when Congress doesn’t pass an appropriations package on time.

Failing to either raise or suspend the nation’s debt limit, before what’s known as extraordinary measures runs out, would likely cause a global financial crisis.

The GOP has been extremely vocal about cutting government spending, but that is separate from addressing the nation’s debt limit, which gives the Treasury Department the borrowing authority to ensure all of the country’s bills are paid in full and on time.

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