Incoming House freshmen routinely enter Congress instantly marked for a re-election challenge by the opposition, but one 2012 winner is facing such political headwinds from within.

California Democratic Rep.-elect Eric Swalwell is hiring staff, awaiting committee assignments and just found a place to live in Washington, D.C., after knocking off the dean of his own party’s congressional delegation. Yet even before being sworn in or casting a single roll call vote, a couple of potential intraparty challengers have appeared in his rearview mirror.

“My back is not big enough for all the targets that are on it,” Swalwell said in a phone interview.

The prosecutor and Dublin city councilman, who just turned 32, capitalized last month on the Golden State’s new top-two primary system to defeat Democratic Rep. Pete Stark, despite being outspent 2-to-1 by the 20-term incumbent.

A widely held assumption for the past year was that a few potential successors to Stark were holding off their ambition until the 81-year-old retired in 2014. At least two had already filed with the Federal Election Commission and began raising money in anticipation of an open-seat race.

Swalwell’s successful candidacy threw a wrench in those gears, and an East Bay seat expected to open in two years is now held by a young upstart with no patience for waiting his turn.

“We’re certainly not here to be a one-hit wonder, so to speak,” Swalwell said. “The best defense is a good offense. If we’re doing our job in the district and delivering on what we told the voters we’d do, I think good things will happen.”

Swalwell, who defeated Stark 52 percent to 48 percent in the 15th District, has some fundraising catching up to do. After spending $764,000 on his race, Swalwell ended the election with just $20,000 in cash on hand.

California Senate Majority Leader Ellen Corbett, who had banked $105,000 in her congressional campaign account by Sept. 30, has begun seeking endorsements for a potential Swalwell challenge. According to a source in the room, Corbett asked for endorsements at an American Israel Public Affairs Committee event last week in Oakland, where Swalwell’s speech received what was described as a rousing ovation.

Ro Khanna, an attorney and former Commerce deputy assistant secretary in the Obama administration, had just more than $1 million in the bank as of Sept. 30. Khanna lives on the district border in Fremont, and his campaign account does not specify which seat he would seek. Khanna said he has not yet made a decision about running.

“I’m right now focused on teaching and practicing law,” Khanna said. “I think it’s premature before the president has even been sworn in, before the new Congress has even been sworn in, to be thinking about the future.”

The 15th is a heavily Democratic district unlikely to ever flip party control, and with the top-two primary system, there is a decent chance Swalwell will never face a Republican in the general election. So it’s not yet clear how much institutional backing the incoming freshman will receive.

The Democratic Congressional Campaign Committee supports incumbents, even in intraparty duels, but resource allocation isn’t decided until later in the cycle, a committee source said. Swalwell said the DCCC did not intervene in his challenge to Stark. The congressional campaign committees typically stay out of contests that do not jeopardize their party’s hold on a seat, even in cases where an incumbent might be vulnerable to an intraparty ouster.

Swalwell, who put in bids for slots on the Armed Services and Transportation and Infrastructure committees, is at Harvard University’s Kennedy School of Government this week with about 50 newly elected members attending a four-day conference on leadership and policy. When the Californian gets to Washington next month, he plans to settle into the spare bedroom of a childhood friend from Dublin, Calif., whom he’ll stay with during the workweek.

He’s currently transitioning out of his roles as Dublin city councilman and Alameda County deputy district attorney. His last council meeting is Dec. 18, and he’ll continue to close out his cases and work on projects in the DA’s office through Dec. 31.

As a prosecutor, Swalwell tried three homicides in the past year, and his work there may have served him well on the trail. He said there is a “corollary” between prosecuting and running for office.

“If you think about it, you’re dealing with jurors who are like voters,” he said. “You’re presenting evidence to them, you’re making a case. Then you’re asking them to do something.”

The University of Maryland graduate interned for then-Rep. Ellen O. Tauscher, D-Calif., one summer during college and worked two jobs to help pay his way — at Tortilla Coast and Washington Sports Club. About a decade later, Swalwell will call colleagues some of the same people he once served dinner and saw at the gym.

Swalwell, who hoped to speak with Stark after the election, said he still has not heard from the outgoing congressman, known for his acerbic personality, or from Stark’s staff.

“The voters in this race, they voted for me and changed out a 40-year incumbent,” Swalwell said. “So I think they’re ready for new energy and ideas, and it’s up to me to deliver what I promised.”