Newly elected members of Congress, from left, Sylvia Garcia (D-Tex.), Alexandria Ocasio-Cortez (D-N.Y.), Debbie Mucarsel-Powell (D-Fla.) and Abby Finkenauer (D-Iowa), gather for a class photo at the Capitol in November. (Melina Mara/The Washington Post)

There is a restiveness in Washington as a new Congress convenes this week.

Democrats will take control of the House at a time of startling upheaval in the federal government. A confrontation between President Trump and Congress over funding for a U.S.-Mexico border wall has partially shut down the government for almost two weeks, with no end in sight, hinting at more conflict in the year to come.

The House’s transformation from a body consumed for eight years by Republican infighting to one dominated by Democrats will be complete as members are sworn in Thursday.

At the center of this drama is a massive class of about 100 freshmen taking the oath of office, including 63 Democrats whose victories pushed Republicans out of power in the biggest party gains since the post-Watergate election of 1974. This group has the chance to be a historic class based on its size and, more important, the unique backgrounds of many newcomers, from the military and intelligence agencies to past Democratic administrations and community activism.

“Their strength is in their unity,” said Rep. Ben Ray Luján (D-N.M.), who helped elect many of the freshmen as the party’s campaign chairman. “To pass legislation out of the House, you need 217 other members raising their hand with you. . . . The new members, 63 strong, are already a quarter of the way there, to be able to deliver those policy shifts.”

But this group includes several young, liberal rising stars and nearly two dozen moderates representing Trump-won districts, potentially competing factions whose priorities Rep. Nancy Pelosi (D-Calif.) will have to balance when she becomes speaker, as is likely. Those tensions are poised to shape legislative efforts on infrastructure, climate change and health care as the party heads toward the 2020 presidential primaries.

Ambitious freshmen may find themselves colliding with the more pragmatic amid the hyperpartisanship of the Democratic search for a nominee to challenge Trump.

Will the freshmen change Washington, or will Washington change them?

Luján, who is assuming a new leadership position as assistant speaker, predicted that the freshmen will bring about a “complete shift with getting things done” in 2019.

“They’re not asking permission to do things,” said Luján, who plans to serve as a liaison between leadership and the freshmen. “They’re going to lean in, and we’re going to achieve success.”

The chamber will be more diverse than at any time in its history. Thirty-three women and 20 people of color are poised to join House Democrats. Caucuses representing African American, Hispanic, Asian American and Pacific Islander, and LGBT lawmakers will see their numbers grow.

More than 20 will have previous military or intelligence service experience, from former Navy SEAL Dan Crenshaw (R-Tex.) to former CIA operative Abigail Spanberger (D-Va.).

The House will welcome countless historic “firsts” — the first Muslim female members, the first Native American female members, the first black women elected from Connecticut and Massachusetts and the first Latinas elected from Texas.

Five freshmen will be 32 or younger, including the youngest woman ever elected to Congress, 29-year-old Rep.-elect Alexandria Ocasio-Cortez (D-N.Y.).

In contrast, House Republicans are projected to be about 90 percent white men, with only one woman — bison farmer Carol Miller (W.Va.) — joining as a new member.

Pelosi praised the number of Democratic women — “up to 95” in the House this year.

“It’ll be a Congress where we will observe the 100th anniversary of women having the right to vote. How appropriate, that we have so many women members to celebrate here for that,” she said in November.

It is not clear how the House’s demographic changes will alter legislation.

Among the identity-based caucuses, the Congressional Black Caucus will be the largest, with 55 members, including nine House freshmen. In a sign of its power, members will include five committee chairs and 28 subcommittee chairs.

“What all of this means for Congress is an expansion of ideas and a new inclusion of experiences that will, in the end, lead to better legislation,” incoming CBC Chairman Karen Bass (D-Calif.) said in a statement.

The Congressional Progressive Caucus also will have more power than at any time in recent history after adding at least 20 lawmakers. Projected to include about 40 percent of House Democrats, the group will be the largest values-based caucus, with several members in Democratic leadership.

Co-chairman Pramila Jayapal (D-Wash.) said the CPC has overhauled its operations to prepare for the new Congress: adding staff, expanding its fundraising and creating nonprofit groups that will help coordinate pressure campaigns with major players on the left.

“We’re building an inside-outside strategy that will help us in key negotiations,” Jayapal said, describing discussions about a “mechanism” — perhaps a scorecard — that would hold self-described liberals to their ideals.

An early priority on the left will find a home with the Select Committee on Climate Change, which Pelosi revived. But divisions have emerged between liberal activists and House committee chairmen on whether the panel should focus on the Green New Deal, a sweeping proposal to get the United States off fossil fuels by 2030 that has been likened to the Marshall Plan.

CPC Co-Chairman Mark Pocan (D-Wis.) played down tensions within the party, saying they were being oversold by Republicans and K Street lobbyists.

“We’re going to come out of the gate as unified Democrats around the issues we campaigned on — raising the minimum wage, an infrastructure bill, prescription drug costs and [political reforms],” he said. “It’s going to be the Senate and the White House that will be our bigger barriers.”

Liberals have drawn considerable media attention since the election, thanks to popular figures such as Ocasio-Cortez and the left’s interest in who will run for president in 2020.

Rep. Jim McGovern (D-Mass.), a member of the Progressive Caucus who will chair the Rules Committee, called for Democrats to push for bold ideas as they take control of one chamber of Congress.

“The bottom line is, you don’t get anything if you don’t ask for it. And if we’re going to have to compromise, let’s not have our opening legislation be the compromise, which we’re going to have to compromise even more on,” he said.

Liberal growth in the House will be matched — if not outmatched — by the rising number of centrist Democrats, after two dozen incoming members won districts Trump carried in 2016.

The moderate New Democrat Coalition inducted 30 members-elect in late November, with Chairman Jim Himes (D-Conn.) praising them as “thoughtful, service-driven leaders who will work across ideologies to get things done.”“We are laser-focused on growing the pie, creating jobs in every part of the country, and building an economy where businesses innovate and create more economic opportunities for more people in more places,” Chairman-elect Derek Kilmer (D-Wash.) said in a statement.

The moderate Blue Dog Coalition is also poised to gain members, with at least seven freshmen already in the fold, according to Chairman Stephanie Murphy (D-Fla.).

“At a time of so much discord in our national politics, people are looking for somebody who’s willing to just put them first and be less about party politics and just be about getting stuff done,” Murphy said. “If you wait until the stars align so that the parties and the people you want are in the seats that you want, you may never have an opportunity to get something done.”

Leaders of the identity-based caucuses cheered their growing numbers.

Four incoming House members are LGBT, doubling the chamber’s number of LGBT lawmakers. Three freshmen are Asian American or Pacific Islander, bringing the total membership of the Asian Pacific American Caucus to 19, a record.

“This increase in AAPIs in the House means AAPI communities will have a louder voice, and our needs will be harder to ignore,” Chairman Judy Chu (D-Calif.) said in a statement.

The Congressional Hispanic Caucus will grow from 31 to 39 members, the largest number since its founding.

CHC Chairman-elect Joaquin Castro (D-Tex.) said the group looks forward to “working with leadership to achieve equal opportunities . . . while at the same time holding this administration accountable for using immigrants and the Latino community as [Trump’s] go-to political piñata.”

Several new members are expected to focus their attention on specific policy issues, driving them into the general debate.

Rep.-elect Lucy McBath (D-Ga.), whose son was fatally shot six years ago, is focused on gun control. Rep.-elect Katie Porter (D-Calif.), a protege of Sen. Elizabeth Warren (D-Mass.), is prioritizing a campaign finance overhaul. Rep.-elect Deb Haaland (D-N.M.), one of Congress’s first Native American women, is calling attention to the issue of missing and murdered indigenous women.

And Rep.-elect Joe Cunningham (D-S.C.), a former ocean engineer, is working on a bill to ban drilling off the Atlantic coast.

“They’re experts in their fields,” Luján said. “The records of service that they’ve all put together, the ideas, especially the fresh ideas that they’re bringing to our nation’s capital — that should all be unleashed.”