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In a speech that was part Democratic campaign push, part policy prescription, President Obama on Monday proposed a $50 billion investment in long-term infrastructure projects that he claimed will stimulate the flailing economy, create jobs and refill the exhausted federal highway trust fund.

Speaking to a crowd of union employees at Laborfest in Milwaukee, the president offered a six-year, front-loaded plan to rebuild 150,000 miles of our roads, lay 4,000 miles of railways and restore 150 miles of airport runways.

The proposal also calls for a strategy to build a national high-speed rail network and create an "infrastructure bank" that uses competitive measures to determine which projects receive funding rather than earmarks and grants.

The president said the project will be paid for -- assuming congressional support -- with tax hikes on oil and gas companies and will cut waste and bureaucracy by consolidating more than 100 duplicative programs.

"This will not only create jobs immediately, it's also going to make our economy hum in the long-run," the president said. "It's a plan that history tells us can and should attract bipartisan support. It's a plan that says even in the still-smoldering aftermath of the worst recession in our lifetimes, America can act to shape our own destiny, to move this country forward, to leave our children something better -- something that lasts."

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But based on the rest of the president's speech -- and congressional Republicans' early reactions -- it is likely to be a tough sell.

"Americans are rightly skeptical about Washington Democrats asking for more of their money -- and their patience," said Senate Minority Leader Mitch McConnell. "After all, they're still looking for the 'shovel-ready' jobs they were promised more than a year ago. A last-minute, cobbled-together stimulus bill with more than $50 billion in new tax hikes will not reverse the complete lack of confidence Americans have in Washington Democrats' ability to help this economy."

A senior official acknowledged before the president's speech that the administration can't estimate how many jobs might be created.

"It would obviously (be) a substantial number of jobs. But just as important is that this would be a sustained program with increased investment over six years so it would be a sustained increase in jobs as well as America's productivity," the official said.

The GOP response shouldn't surprise Obama, who used much of his speech to accuse Republicans of rejecting plans to strengthen the middle class and rebuild the economy.

"Even on things we usually agree, they say no," Obama said of the GOP. "They just think it's better to score political points before an election than to solve problems."

In a combative tone, the president pointed specifically to House Minority Leader John Boehner as he laid into Republicans for objecting to a package last month that sent $26 billion to the states to keep teachers on the payroll and pay for police officers by sending additional Medicaid money so states could redirect that cash for salaries. The bill was paid for with cuts to expanded food stamp payments and higher taxes on multinational corporations.

"You know how we paid for it? By closing one of these ridiculous tax loophole that actually rewarded corporations for shipping jobs and profits overseas," Obama said. "Even a lot of America's biggest corporations agreed that this loophole didn't make sense, agreed that it should be closed, that agreed that it wasn't fair -- but the man who thinks he's gonna be speaker, he wants to re-open this loophole."

Obama said he doesn't want to re-live the past when Republicans led Congress, arguing that not only does the GOP not have new ideas, but the party wants to return to past policies that put the country on a downward spiral.

"These are the folks whose policies helped devastate our middle class. They drove our economy into a ditch. ... And then they've got the nerve to ask for the keys back," Obama said.

But Republicans offered a few reminders for voters as well. Boehner issued a statement recalling that the Obama administration said if the $814 billion stimulus bill passed, unemployment would not rise above 8 percent. It now stands at 9.6 percent, its 19th consecutive month above 8 percent and 16th consecutive month above 9 percent.

"If we've learned anything from the past 18 months, it's that we can't spend our way to prosperity," Boehner said in a statement. "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."