Washington ? Republicans have significantly narrowed the gap with Democrats on who is trusted to deal with the country’s problems and have sharply reduced several of President Obama’s main political advantages, according to a new Washington Post-ABC News poll.

The survey paints a portrait of a restless and dissatisfied electorate at the beginning of a critical election year. More than seven in 10 Americans disapprove of the job Congress is doing, and as many say they’re inclined to look for new congressional representation as said so in 1994 and 2006, the last times that control of Congress shifted.

Asked how they would vote in the November House elections, Americans split evenly — 46 percent siding with the Democrats, 46 percent with the Republicans. As recently as four months ago, Democrats held a 51 to 39 percent advantage on this question.

Obama’s overall approval rating is holding steady, with 51 percent of respondents giving him positive marks and 46 percent rating him negatively. On the big domestic issues — the economy, health care, jobs and the federal budget deficit — bare majorities of Americans disapprove of the job he is doing.

Only on fighting terrorism does Obama receive majority support for his performance, with 56 percent saying they approve. But the poll shows majority opposition to the administration’s plan to try terrorism suspects in federal courts.

Changes in public attitudes were most apparent when Americans were asked whether they trust Obama or congressional Republicans to handle these issues. Last summer, the president enjoyed advantages of more than 20 points over the GOP on the handling of health care, the economy, the deficit and the threat of terrorism. Those leads have all slipped, reflecting both the partisan polarization that has colored the political landscape for many months and the sharp erosion in support for Obama among independents.

But there is about as much time between now and November as has elapsed since Obama held his June advantages. The president and his allies have started a new political offensive, seeking to rebound from the party’s loss of the Massachusetts Senate seat long held by the late Edward M. Kennedy and salvage their effort to enact comprehensive health-care reform.