Rep. Chris Van Hollen (D-Md.) is running to succeed retiring Sen. Barbara A. Mikulski (D-Md.). (Sarah L. Voisin/The Washington Post)

It’s a good time to be Rep. Chris Van Hollen.

His party is favored in the race for the White House, he’s overwhelmingly expected to win the seat of retiring Sen. Barbara A. Mikulski (D-Md.), and — no matter which way the balance of power in the upper chamber falls — he stands to benefit.

If Democrats win control of the Senate, experts say, a possible President Hillary Clinton would need allies there who have relationships in the House of Representatives, so she can try to win Republican support for her agenda. If Republicans keep their Senate majority, Clinton would need Democrats in that chamber who can negotiate good-faith deals with leadership.

That means Van Hollen (D-Md.), a polite and well-liked policy wonk who was a top lieutenant to House Minority Leader Nancy Pelosi (D-Calif.), should find multiple ways to flex his budget, foreign affairs and political muscles.

“The Senate provides a lot of potential influence to individual senators,” he said in an interview, pausing to knock on a wooden table. “If all goes well, I look forward to creatively using that influence for the benefit of the whole state, not just one congressional district.”

After defeating House colleague Donna F. Edwards (D-Md.) in a bitter primary, Van Hollen, 57, faces statehouse Minority Whip Kathy Szeliga (R-Baltimore County) in the general election. A father of three who lives with his wife, Katherine, in Kensington, Md., he would be Maryland’s first senator from the Washington suburbs since Silver Spring attorney Blair Lee, who served a century ago.

Van Hollen has campaigned vigorously across the state, presenting himself as a get-it-done legislator who can bridge deep partisan divides, and parrying Szeliga’s criticism of his support of President Obama’s Iran deal and Hillary Clinton.

Maryland Del. Kathy Szeliga (R-Baltimore County) and Van Hollen debate at WAMU-FM (88.5) in Washington. (Lloyd Fox/Baltimore Sun)

While his opponent touts the surprise 2014 victory of Gov. Larry Hogan (R) as proof she can win in deep-blue Maryland, experts say the Democrats’ 2-to-1 voter registration advantage is a much steeper hurdle when the White House is also in play. Van Hollen has raised vastly more money than Szeliga, and was nearly 30 points ahead of her among likely voters in a recent Washington Post-University of Maryland poll.

“In presidential election years, if you’re a Democrat running for statewide office, you’re the only game in town,” said Todd Eberly, a political science professor at St. Mary’s College of Maryland.

Climbing the ladder

The son of a Foreign Service officer, Van Hollen was active in the anti-apartheid movement as a student at Swarthmore College. After graduation, he earned a graduate degree from Harvard University’s John F. Kennedy School of Government.

In the late 1980s, he worked on Capitol Hill for Sen. Charles Mathias (R-Md.) and the Committee on Foreign Relations, then advised Gov. William Donald Schaefer (D-Md.) while attending Georgetown University Law Center. He ran for state legislature in 1990, driven by concern about overcrowded classrooms and underfunded schools in his home base, Montgomery County.

After 12 years in Annapolis, Van Hollen won a House seat in 2002, narrowly beating eight-term Republican congresswoman Connie Morella after redistricting removed a chunk of GOP voters from the affluent and liberal 8th District. He had the opportunity to join the House Committee on Government Reform, chaired at the time by one of Morella’s good friends, then-Rep. Thomas M. Davis III (R-Va.). Davis was not sure what to expect.

“He was surprisingly easy to work with,” Davis said of Van Hollen. “We had differences, but we would always work them out.”

On issues such as Metro, which tends to unite Virginia and Maryland lawmakers regardless of party, Van Hollen put the region first, Davis said.

He served as chairman of the Democratic Congressional Campaign Committee in 2008, when the party picked up a slew of seats amid Obama’s election, and he stayed on for a second, dismal cycle in 2010 before becoming the top Democrat on the House Budget Committee.

In between, Pelosi named him her assistant, a leadership role that gave him juice among his colleagues and rivals, and made some wonder why he so quickly threw his hat into the senatorial ring when Mikulski announced her plans to retire.

“He could have been speaker of the House, if he stuck around,” Davis said.

From left: Van Hollen and Reps. Nancy Pelosi (D-Calif.) and Steny H. Hoyer (D-Md.) speak at the Capitol in September 2013 after the Senate rejected budget legislation passed by the House. (Joshua Roberts/Reuters)

Van Hollen counts among his accomplishments helping to pass the high-profile Affordable Care Act, as well as the lesser-known ABLE Act, which allows families to open tax-advantaged accounts for children with disabilities. Sen. Robert P. Casey Jr. (D-Pa.), the Senate sponsor of the bill, said he relied on Van Hollen to interpret its progress in the lower chamber in real time.

“In our business, you’re not often on the telephone late at night with a House member,” Casey said. “Several nights I had to call Chris and say, ‘This is what so-and-so said — What’s it mean?’ He was a great guide.”

Van Hollen also was part of a bipartisan budget committee devoted — unsuccessfully, it turned out — to negotiating a spending deal both parties could stomach. He jokingly calls it the “not-so-super committee.”

In the 2012 presidential election, he helped Vice President Biden prepare for his nationally televised debate by playing the part of his opponent, Rep. Paul D. Ryan (R-Wis.), now the House speaker.

Words that counted

When Van Hollen decided to run for Senate, he quickly secured the endorsement of Minority Leader Harry M. Reid (D-Nev.), who paints the congressman as a person of substance comfortable with numbers.

“In leadership meetings we had with Pelosi, he didn’t talk a lot. But when he did, it was important,” Reid said.

His backing did not keep Edwards from launching her own campaign, and the race between the two neighboring House members turned ugly when the abortion rights women’s group Emily’s List threw its considerable weight behind Edwards.

Mikulski, the longest-serving woman in congressional history, also stayed silent through the primary. She now says she is “excited about passing the torch” to Van Hollen.

“It is time for new leadership,” she said in an interview. “With his savvy, his know-how, his commitment, he’ll be a very fine senator.”

Sen. Barbara A. Mikulski (D-Md.) and then-Sen. Hillary Clinton (D-N.Y.) join Van Hollen at a reception at the Women’s Club of Chevy Chase in 2001. (Robert A. Reeder/The Washington Post)

One of the first challenges facing whoever wins the election will be beating out Virginia in the competition to host a new FBI headquarters, an accomplishment Mikulski had wanted to achieve before the end of her tenure. The General Services Administration recently delayed the decision until March.

Van Hollen’s interest in tackling global warming, the budget deficit and the nation’s role in conflicts around the globe could land him on Foreign Relations, Budget or even Judiciary committees, those close to him say. Others speculate that he could run the Democratic Senatorial Campaign Committee one day.

Gun control advocate Vincent DeMarco, who is president of Marylanders to Prevent Gun Violence, said he hopes Van Hollen would continue the battle for stricter gun laws that he began in the House.

Not a red meat guy

As a candidate, Van Hollen has taken nothing for granted, campaigning hard for Clinton as well as himself. Appearing at the Democratic Club of the retirement community Leisure World the other day, he cautioned against complacency, reminding his audience of recent elections around the world that did not go according to projections.

Van Hollen gets a hug from Theda Rosenblum at Leisure World in Silver Spring, Md. (Sarah L. Voisin/The Washington Post)

Voters in Colombia failed to ratify a peace deal ending a war with guerrilla fighters, for example, he said. And Britain voted to leave the European Union.

Ticking off a litany of what he called Republican nominee Donald Trump’s most outrageous comments, Van Hollen said: “It would be a very scary thing if he were ever to get close to the White House.”

He admonished supporters of Sen. Bernie Sanders (Vt.) to come around for Clinton, saying that a decision not to vote or to choose a third-party candidate could hurt the Democrats. Green Party candidate Margaret Flowers is also running for Mikulski’s Senate seat.

Then he quoted Biden: “Don’t compare me to the almighty, compare me to the alternative.”

In an otherwise wonky and forgettable diatribe, the line earned Van Hollen a big laugh.

Earlier that day, he attended a protest outside Trump International Hotel in Washington organized by the Service Employees International Union, a labor group that helped propel Edwards into office in the House in 2008 but endorsed Van Hollen over her in the Senate primary.

The would-be senator yelled into a bullhorn on Pennsylvania Avenue NW, as workers and organizers waved red and white “Boycott” signs. They wanted people to stop buying Trump products in solidarity with workers at his Las Vegas high-rise, who say Trump has refused to negotiate with them in good faith.

Van Hollen speaks to union workers as they picket outside the Trump International Hotel in Washington on Oct. 13. (Nikki Kahn/The Washington Post)

“Get back to the negotiating table, Mr. Trump,” Van Hollen shouted. “You can run, but you can no longer hide from the working people.”

But Davis, the former GOP congressman from Virginia, said Van Hollen’s natural role is not throwing red meat to the base.

“He’s a Boy Scout in a world where that doesn’t always get rewarded,” he said.

Emily Guskin contributed to this report.