Democrat Doug Jones was sworn in Wednesday as Alabama's newest U.S. senator, reducing the Republican advantage to 51 to 49 and giving his party more room to impede President Trump's 2018 legislative agenda.

Jones took his oath of office alongside former vice president Joe Biden, a longtime friend who had urged him to run last year. Tina Smith (D-Minn.) was also sworn in Wednesday to replace former senator Al Franken; she was joined by former vice president Walter Mondale.

The arrival of Smith and Jones on Capitol Hill highlighted the extent to which the #MeToo movement has swept over Washington. Jones defied the political tilt of his state by defeating Republican Roy Moore, who was accused of making unwanted sexual advances toward teenage girls when he was in his 30s. Smith's predecessor, Franken, resigned under pressure from fellow Democrats after allegations emerged that he had touched women inappropriately.

Even before it was clear what committees Jones would serve on, the Alabama Democrat was already playing an outsize role. His presence allows Democrats to block any Trump nominee, or any legislation, by winning just two Republican defectors. Vice President Pence can break 50-to-50 ties.

Senate Republican aides privately conceded that Jones's vote will make it nearly impossible to take another run at repealing the Affordable Care Act and may quiet talk of a push for a major entitlement overhaul this year.

Jones did not telegraph what he would do with his influential position as he shuttled between engagements in the Capitol on Wednesday. As he did as a candidate, Jones presented himself as a compromiser, even though many of his views align much more closely with the Democratic Party.

"I think any good senator is a bipartisan, and that's what I'm looking to do," Jones said as he walked through the Capitol for his swearing-in.

Sen. Joe Manchin III (D-W.Va.), who like Jones represents a heavily conservative state, said Wednesday was the first time he had met the Alabamian.

"I said 'Welcome to the radical middle,' " Manchin said, recounting their chat.

Jones, 63, became the most junior member of the Senate, just behind Smith. After being officially sworn in, the two of them, accompanied by their families and guests, walked to the Old Senate Chamber for a reenactment. Biden watched from a few feet away.

"Smile, man, smile!" Biden urged. As he walked toward Jones and Pence, who administered the oath of office, Biden said that Alabama's last Democratic senator, for whom Jones once worked, would be proud of him.

"Howell Heflin's looking at you," Biden of the senator, who died in 2005.

Later, Jones attended a welcome reception in the Kennedy Caucus Room of the Russell Senate Office Building, where potential 2020 Democratic presidential candidates Sens. Elizabeth Warren (D-Mass.), Kirsten Gillibrand (D-N.Y.) and Cory Booker (D-N.J.) were on hand. Booker traveled to Alabama during the final weekend of the campaign to stump for Jones.

As he rode a subway in the Capitol minutes after Jones was sworn in, Sen. Tim Kaine (D-Va.), who frequently spoke with Jones during his run, said in an interview that Jones has enough time to establish a record he can run on back home.

"He's not to represent D.C. to Alabama," Kaine said. "He's to represent Alabama to D.C."

Kaine drew a comparison between Jones's campaign and Democrat Ralph Northam's winning run for governor in Virginia.

"His personality is not that different from the Ralph Northam personality," said Kaine, who faces reelection this year. "In a time where I think a lot of people are worried about the divisiveness of the president, I think they viewed Ralph, they view Doug, as somebody who can bring people together."

Jones is a former U.S. attorney who is well known in Alabama for prosecuting two men for the bombing of a black church in Birmingham that killed four girls. It is not yet clear whether Jones will get a seat on the Senate Judiciary Committee; there is pressure in the chamber to give Sen. Kamala D. Harris (D-Calif.) the seat on the panel that opened when Franken resigned.

Some Democrats have described Jones's win over Moore as a model for how they can take back at least one chamber of Congress in this year's midterm elections. Republicans have described the Alabama race as a fluke, one that tipped the wrong way after Moore was nominated and faced allegations of sexual misconduct, the first of which were reported by The Washington Post.

The Democratic Party, however, has seen polling on the race that found it unusually tight even before Moore became buried by scandal. In 2016, Trump carried Alabama by 28 points; two years earlier, Democrats could not find a credible candidate to run for the seat then held by Republican Jeff Sessions, now the attorney general.

But Manchin was not looking to draw any similarities between Jones's campaign and his own race this year, a top target for Republicans.

"I'm going to be me. I'm Joe," he said.

Jones, who is friendly with several of his new colleagues, said before and after the election that he would be an "independent" senator voting for whatever was good for his state. In an interview with The Post in the fall, Jones identified several senators who he said are models for the kind of consensus-driven governance he touted on the campaign trail: Kaine, Patty Murray (D-Wash.), Lamar Alexander (R-Tenn.) and John McCain (R-Ariz.).

On most of the pressing issues the Senate faces this year, however, Jones has been critical of the Republican majority. He used his victory speech to call for the Children's Health Insurance Program, or CHIP, to be fully funded. He has argued that hundreds of thousands of Americans brought to the United States as children should be allowed to stay and opposes the president's demand that Congress fund a wall on the Mexico border as part of any fix.

"I don't think that's an expense taxpayers should have to incur," Jones said last month.

In one interview with The Post last year, Jones also said that he wanted Congress to pass a new bill to "reinvigorate" the Voting Rights Act, that he would have cast a deciding vote to block Betsy DeVos from becoming education secretary and that he would oppose judicial nominees who came off as overly "political."

Senate Minority Leader Charles E. Schumer (D-N.Y.) said Jones and Smith "will add to the diversity and energy of our caucus," and he predicted that both will become influential voices in the upper chamber. He mentioned CHIP and said, "I hope we can get that done for his state."

Republicans have already warned that Jones, who next faces voters in 2020, will create trouble for himself if he sides too frequently with Democrats. In a statement after Jones's win, Sen. Cory Gardner (R-Colo.), who runs the National Republican Senatorial Committee, said that Jones should "do the right thing and truly represent Alabama by choosing to vote with the Senate Republican Majority."

After the swearing-in ceremony, dozens of Jones's guests headed to a hearing room in the Russell Senate Office Building, around the corner from the new senator's office. Among them were Birmingham Mayor Randall Woodfin, Jones strategist Joe Trippi and political strategist James Carville.

Sen. John Barrasso (R-Wyo.), a physician who has been one of the GOP's point people on health care, walked past the welcome party on his way to a Fox News interview. Asked how Jones's arrival in the Senate would affect the Republican agenda, Barrasso said he had not talked to him about it yet.

Paul Kane contributed to this report.