Treasury Secretary Tim Geithner will try out a more political line of attack on Wednesday, whacking Republicans over their economic record.

Geithner will go after the GOP in a speech Wednesday afternoon, joining with President Obama and congressional Democrats in underscoring the differences between their approach and Republicans' approach to the economy.

"In the 1990s, the government put an end to budget deficits, and America enjoyed a period of growth led by the private sector where prosperity was widely shared and job creation was robust," Geithner will say this afternoon during a speech at the Center for American Progress, a liberal think tank. "Over the next decade, Washington tried a new path, running up huge debts, while incomes for most Americans stagnated and job creation was anemic."

Geithner has been giving a number of interviews and making speeches this week to promote the administration's accomplishments on Wall Street reform. But he's also taken a more prominent role in defending President Obama's stewardship of the economy during an election season in which Republicans have targeted the administration on that very issue.

The Treasury secretary said the U.S. is suffering from the damage caused by "misguided policy" that the GOP had sought when they were last in power. He warned of a "false prosperity" that would be fostered by Republicans' plans, which he said would create debt and stifle growth.

Geithner's words are well in line with what Democrats and the president himself have warned in recent weeks, which is that a return to Republican control of Congress in this fall's elections would mean a reversion to past policies.

But Republicans have shot back by blaming Obama and Democrats' policies for running up the deficits. They've argued Democratic lawmakers would raise taxes on small businesses by letting income taxes for top earners spring upward when they expire at the end of the year.

Geithner will take direct aim at that argument in his speech.

“Borrowing to finance tax cuts for the top 2 percent would be a $700 billion fiscal mistake," he'll say. "It’s not the prescription the economy needs right now, and the country can’t afford it.”