MILWAUKEE — A combative U.S. President Barack Obama rolled out a long-term jobs program Monday that will exceed $50 billion to rebuild roads, railways and runways, and coupled it with a blunt campaign-season assault on Republicans for causing Americans' hard economic times.

Republican leaders instantly assailed Obama's proposal, which is also likely to be met with reluctance by many Democrats to approve additional spending and higher federal deficits just weeks before elections that will determine control of Congress.

That left the plan with low odds of becoming law this year. Jim Manley, spokesman for Senate Majority Leader Harry Reid of Nevada, cautioned, "If we are going to get anything done, Republican co-operation, which has been all but non-existent recently, will be necessary."

Administration officials said that even if the program somehow won quick congressional approval, it would not produce jobs until sometime next year. That means the proposal's only pre-election impact may whether voters interpret it as a serious effort by the White House to boost the economy and create jobs.

In remarks prepared for delivery to a Labor Day speech in Milwaukee, the president said Republicans are betting that between now and Election Day on Nov. 2, Americans will forget the Republican economic policies that led to the current recession.

"These are the folks whose policies helped devastate our middle class and drive our economy into a ditch. And now they're asking you for the keys back," Obama said.

The president said Republicans have opposed everything he has done to strengthen the economy.

"They think it's better to score political points before an election than actually solve problems," he said.

He added, "Even as we speak, these guys are saying no to cutting more taxes for small business owners. I mean, come on! Remember when our campaign slogan was "Yes We Can?" These guys are running on "No, We Can't," and proud of it. Really inspiring, huh?"

Republicans made it clear that Obama can expect no help from them.

Senate Republican Leader Mitch McConnell said the plan "should be met with justifiable skepticism" because it would raise taxes, while Americans are "still looking for the 'shovel-ready' jobs they were promised more than a year ago" in the $814 billion economic stimulus measure.

The House of Representatives Republican leader, John Boehner, added "We don't need more government 'stimulus' spending. We need to end Washington Democrats' out-of-control spending spree, stop their tax hikes, and create jobs by eliminating the job-killing uncertainty that is hampering our small businesses."

Administration officials said the initial $50 billion would be the beginning of a six-year program of transportation improvements, but they did not give an overall figure. The proposal has a longer-range focus than last year's economic stimulus bill, which was more targeted on immediate job creation.