WASHINGTON — The House yesterday approved an extra three months of jobless benefits for all unemployed Americans, knowing the plan’s chances are slight in the Senate and almost nonexistent at the White House.

After failing to get a veto-proof two-thirds margin by three votes on Wednesday, Democrats got an exact two-thirds margin yesterday with a 274-137 vote — the amount needed to overcome a threatened presidential veto.

Democrats said they pushed the legislation through to the Senate because Americans need help in a slumping economy.

The Labor Department reported yesterday that the number of people filing new claims for unemployment benefits last week increased by 25,000 from the week before.

The unemployment rate in May jumped to 5.5%, up from 5% in April. It was the biggest one-month gain in 22 years.

“The American people are waiting to see if Congress is going to help them,” the speaker of the House, Nancy Pelosi, a Democrat from California, said.

But the White House already has threatened to veto the bill, and Senate Democrats have said they won’t try and force their Republican colleagues to consider the House legislation.

The majority leader of the Senate, Harry Reid, a Democrat from Nevada, said he will try to bring up the House bill, but he won’t force the issue if Senate Republicans object.

“We’re not wasting weeks” on it, he said. Instead, Mr. Reid said, Democrats might attach the jobless benefits extension to the Iraq war spending bill, a move also opposed by the White House.