President Barack Obama used a formal unveiling of his stimulus package Wednesday as a chance to make the case for his efforts to right the nation’s foundering economy, while leveling some of his harshest criticism ever against his GOP detractors.

Billed as an announcement of his $50 billion infrastructure spending package along with targeted tax cuts to stimulate the economy, Obama’s speech in Cleveland sounded more like a campaign stump speech.

Obama kicked off the speech with criticisms of the Bush administration’s economic policies, arguing that the reliance on tax cuts and lifting of regulatory controls “gave us the illusion of prosperity,” which proved to be short-lived and ultimately caused the economic collapse.

Obama argued that as a result, “with the nation losing nearly 800,000 jobs the month I was sworn in, my most urgent task was to stop a financial meltdown and prevent this recession from becoming a second depression. … We’ve done that. The economy is growing again.”

Obama acknowledged that economic “progress has been painfully slow.” The president also conceded that many voters believe that his early efforts to end the recession were simply helping corporate interests, saying, “some of the very steps that were necessary to save the economy — like temporarily supporting the banks and the auto industry — fed the perception that Washington is still ignoring the middle class in favor of special interests.”

Obama then pivoted to a direct attack on House Minority Leader John Boehner (Ohio), accusing him of not being willing to accept Republicans’ role in the economic collapse and complaining that he and other Republicans have not offered new policy prescriptions.

“It would be one thing if he admitted his party’s mistakes during the eight years they were in power, and was offering a credible new approach to solving our country’s problems. But that’s not what happened. There were no new policies from Mr. Boehner,” Obama said.

Obama spent much of the speech attacking Boehner, repeatedly deriding Republicans’ opposition to infrastructure spending proposals and other Democratic policy plans while arguing that the GOP has been more than willing to accept the political credit for them. “Mr. Boehner and the Republicans in Congress said no to these projects … though I should say that didn’t stop a lot of them from showing up at the ribbon-cutting ceremonies and trying to take credit,” he said.

Even when making the case for his stimulus plans, Obama used the speech to hammer Boehner. For instance, when arguing for a permanent extension of tax credits for the middle class, Obama accused Boehner of holding them “hostage” until Democrats agree to also extend tax cuts for the nation’s wealthiest citizens.

“Let me be clear to Mr. Boehner and everyone else: We should not hold middle-class tax cuts hostage any longer. We are ready this week to give tax cuts to every American making $250,000 or less. For any income over this amount, the tax rates would go back to what they were under President Clinton,” Obama said.

Despite his vigorous defense of his proposals, it appears unlikely Congress will move on them, particularly since even Democrats are unenthusiastic at best about the plan.

Sen. Michael Bennet announced Wednesday he would oppose Obama’s latest stimulus proposal, just hours before the president was scheduled to unveil the package of spending and tax proposals.

In a statement released by his office, the Colorado Democrat said that while he would back a handful of tax-credit proposals that could benefit his state, he would not support Obama’s broader plan.

“I will not support additional spending in a second stimulus package. … Public-private partnerships that improve our infrastructure are a good idea, but must be paid for, should not add a dime to the deficit, and should be covered by unused Recovery Act dollars,” Bennet said.

Bennet, who is facing a difficult election this fall, is the latest Democrat to throw cold water on Obama’s plan. On Tuesday, House Majority Leader Steny Hoyer (Md.) cast doubt on the likelihood Congress would approve the package this year, saying that, “It will be very difficult to get a very broad agenda through … because Republicans’ obstructionism has, in effect, not allowed us to do some of the job-creating actions that we want.”