WASHINGTON — Buoyed by a string of Republican retirements and President Trump’s persistently low approval rating, Democrats are increasingly hopeful about their chances for a midterm election wave that would give them control of the House and deliver a blow to the president.
The number of Republicans bowing out rather than bearing down for tough races is the latest worrisome sign for the GOP. Combine that with Trump’s ability to unite Democrats in opposition and historical headwinds, and some Democrats are optimistic.
‘‘We don’t have an Obama figure energizing us; we have Trump energizing us,’’ said Democratic Representative Gerald Connolly of Virginia, as he described standing-room-only gatherings at local Democratic events.
‘‘Who is the D? Show me who the D is, so I can vote for them,’’ he said of voter sentiments. ‘‘I think it’s shaping up into that kind of election.’’
Representative Ben Ray Lujan of New Mexico, who is leading Democrats’ House campaign effort, said there is a ‘‘clear path to a majority,’’ something he said he never saw in 2016.
Indeed, Trump’s job approval rating — a key indicator in midterm elections — lags below 40 percent in most polls, and marks for Congress are half that.
Since Trump’s inauguration, Democrats have won state legislative elections across the country, reclaimed the Virginia governor’s seat by a surprising 9-percentage-point margin, and managed an upset Senate victory in GOP-dominated Alabama, albeit with the help of a Republican nominee accused of sexual misconduct with teenage girls.
The next test is in Pennsylvania, where a March special election to replace Republican Representative Tim Murphy, who resigned amid allegations he asked a woman he was having an affair with to get an abortion, will become another test of momentum.
Trump is expected to campaign for the Republican candidate, state Representative Rick Saccone.
Even House Speaker Paul Ryan concedes that his party may have to ‘‘buck history’’ for him to keep his job, though he maintains that voters will reward Republicans after their sweeping tax cuts.
‘‘The reason I feel confident and comfortable is because we ran on a set of ideas and policies, we’re now executing those ideas and policies, and the results are proving themselves,’’ Ryan said Friday in Wisconsin.
Nonetheless, the environment has contributed to a steady stream of Republican retirements. This week, Ed Royce and Darrell Issa of California, two of the more vulnerable GOP members, announced they would not run again.
Altogether, 31 House Republicans have announced their retirements so far, ahead of a typical election-year pace and giving rise to comparisons with 1994, 2006, and 2010, the last three times that voters flipped control of the chamber.
Ohio Representative Steve Stivers, who heads the GOP’s House campaign operation, says he believes the retirement run is near its end, but he and other Republicans concede that the later the retirements, the harder it is for candidates to step in and build the campaigns necessary to win.
National Democrats, meanwhile, are targeting 91 House districts — a list that covers nearly all the GOP vacancies — and they say they have ‘‘viable’’ candidates in 87 of those districts.
Since World War II, the president’s party has never gained seats when the president’s job approval rating is below 50 percent, a threshold Trump has yet to reach.