Updated November 13, 2022 at 12:30 PM ET

Despite some very tight races, Democrats have held on to their slim majority in the U.S. Senate.

The chamber was decided Saturday evening after Nevada Sen. Catherine Cortez Masto defeated Republican nominee Adam Laxalt, a former state attorney general, according to a race call by The Associated Press.

That gives Democrats 50 Senate seats, which is enough for the majority with Vice President Harris' tiebreaking vote.

The U.S. House remains up for grabs, with Republicans maintaining a narrow inside track to the majority.

Nevada was one of Republicans' top targets, and Cortez Masto's reelection was a toss-up coming into the election. She was running neck and neck with Laxalt, Nevada's former attorney general who was endorsed by former President Donald Trump.

As of the AP race call, Cortez Masto had a lead of about 5,000 votes.

Democrats could add to their margin in the Senate, if incumbent Raphael Warnock defeats Republican challenger Herschel Walker in a runoff in Georgia on Dec. 6.

Another factor that played a role in Democrats' defending their majorities is the issue of abortion rights. After the Supreme Court overturned Roe v. Wade in June, researchers saw a distinct increase in voter registration among women and young people. While national polls indicated that the economy and inflation were top of mind, there's no doubt that the issue of abortion rights played a crucial role in motivating voters and increasing fundraising for Democratic candidates.

In an interview with NPR's Weekend Edition Sunday, Sen. Amy Klobuchar, D-Minn., said it had been "a great week for democracy" and attributed her party's success to strong candidates "who had experience, who knew how to get things done."

"[T]he reason there wasn't a red wave is because Democrats had a 'blue wave of accomplishment' and we basically defied the tides of history," she said, quoting Senate Majority leader Chuck Schumer, D-N.Y.

So what do Democrats understand that voters have asked them to do? Klobuchar said the party's mandate was first, to bring down costs, including pharmaceuticals, protect Social Security and Medicare, and "do all we can to get our economy in a place that works for everyone."

Second, she says, is to codify Roe v. Wade. "We don't know what's going to happen with the House ... We don't know if the Republicans will play ball. I'd get rid of the filibuster to do it."

And third is to protect democracy. "A lot of the election deniers lost," Klobuchar noted. "So it shows Americans care about democracy."

If Republicans take the House, it's unlikely the two chambers will find much common ground and the dynamic tees up some clashes over government funding bills and increasing the debt ceiling. A Democratic hold of the House would mean President Biden's party would maintain its trifecta of power for another two years.

In the Senate, questions of whether to modify the filibuster will likely also take center stage, as Democrats still remain short of a 60-vote supermajority and would need to bypass the filibuster if they want to pass major legislative priorities.

A secure Democratic majority in the Senate also preserves Democrats' ability to approve Biden's nominees, including any future vacancies on the U.S. Supreme Court.

Earlier this cycle, Senate Minority Leader Mitch McConnell predicted there was a "greater likelihood the House flips than the Senate," citing, in part, "candidate quality."

The effect that former president Donald Trump had on his party's fortunes is under scrutiny, as many of his hand-selected candidates lost.

Liam Donovan is a former GOP campaign strategist, now with lobbying firm Bracewell LLP. He told NPR's Ayesha Roscoe that the Republican establishment is now "rethink[ing] whether he is a net positive in this party going forward. Now, do the voters agree? That question remains unsettled."

Trump's involvement affected which candidates decided to enter races nationwide – with many that did eventually losing in the general election in races considered winnable by Republicans.

"Republicans lost the Senate in 2010 and 2012 because they put up poor candidates," says Donovan. "The difference [in 2022] is that President Trump, I think, locked these fields into questionable candidates. You had people that might have been the strongest staying out because they didn't want to go anywhere near this. You had a number of strong governors who might have come in and easily won these seats that stayed out."

Trump, he says, is "somebody that people don't necessarily want to grapple with."

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