The White House hopes to squeeze maximum political mileage out of the White House event, surrounding Mr. Obama with families and workers who would benefit from the extension. On Tuesday, he will take his message to Iowa, the battleground state that turned him into a serious presidential contender in 2008.

In Cedar Rapids, Mr. Obama plans to visit the home of Jason and Ali McLaughlin, a high school principal and an account manager at a document-scanning company, a campaign official said. The McLaughlin family, with a combined income of $82,000, would face an extra $2,000 burden next year if the tax cuts on the middle class expired as scheduled, the campaign said.

White House officials insisted that Monday’s move was more than politics. They said it would ease anxiety over the “fiscal cliff” — the combination of tax increases and automatic spending cuts that are scheduled to kick in at the end of this year. That one-two punch, economists say, could deal a heavy blow to an already tender economy unless the White House and Congress work out some kind of compromise.

Proposing a one-year extension, a senior official said, recognizes that Mr. Obama and the Republicans are not likely to resolve the larger debate over whether to extend the Bush tax cuts for everyone or, as Mr. Obama has long advocated, just for the middle class. That debate is likely to be decided at the ballot box, where a victory by Mr. Romney would almost certainly enshrine all the tax cuts.

“To the degree that there is concern about the economy, we’re saying, ‘Let’s extend the middle class tax cuts for a year,’ ” said Gene B. Sperling, director of the White House’s National Economic Council. “Economically, extending tax cuts to those workers will have the most effect on them and the strongest impact on the economy.”

A one-year extension for people making under $250,000 would cost the government $150 billion in revenue, the administration estimates, an amount that would be added to the deficit. In a point of comparison, economists estimate that letting the cuts expire for people above that threshold would generate $850 billion over 10 years.

While Mr. Obama returns to the tax issue this week, House Republican leaders will press forward Wednesday with a vote to fully repeal his health care law, testing their faith that they can make the law part of their attack on Democratic economic policies against evidence that swing voters want to move past the fight.