MILWAUKEE - As Wisconsin voters head to the polls today, the state's most controversial congressman, Rep. Paul Ryan, ripped President Obama's criticism of his budget proposal and praised Mitt Romney - a man he endorsed last week - for "relishing" the debate over how to solve the nation's fiscal mess.

Earlier today Obama called Ryan's budget proposal "thinly veiled social Darwinism," saying it was "disguised as deficit reduction plans" but "really an attempt to impose a radical vision on our country." That was a charge denounced by Ryan in a phone interview with ABC News this evening.

"Desperate and demagogic is how I would describe his speech in two words," Ryan said. "Unfortunately we've become accustomed to this kind of rhetoric from the president. I feel like it's Groundhog Day, except it's April. He essentially said the same thing last year.

"His speeches are becoming more partisan and desperate by the day and his attempts to divide the nation and to distract people from his own failure to lead - I just don't think are going to work," he continued. "I think people are smarter than that.

"The president's attacks on our budget are as disappointing, as revealing as his attacks on the Supreme Court," Ryan said. "It seems that he takes anyone questioning his vision of limitless government as a personal affront and he's lashing out. That's hardly the kind of leadership we were expecting when he ran for office."

Ryan, who announced his support for Romney last Friday, is chairman of the House Budget Committee and has come in for withering criticism from Democrats such as the president for a budget plan to transform Medicare and Medicare that he says would give states and individuals more choices while slashing government spending.

The Ryan budget has added fuel to the fire of how to address the nation's soaring deficits, with Republicans rallying around it and Democrats arguing that it will destroy the social fabric of the country. Earlier today, Obama called the Ryan budget the Republicans' "governing platform."

"This is what they're running on," the president said.

Given the White House's full-throated attack on Ryan's budget, Romney's decision to praise the proposal, campaign around Wisconsin with Ryan, and - possibly - to pick him as a running mate later this year, does carry some risks. Romney has praised Ryan's plan as "a bold and exciting effort" that is "consistent" with his own proposal.

"I applaud it," Romney said last month of Ryan's budget. "It's an excellent piece of work and very much needed."

While Ryan would not discuss any veepstakes possibilities - "I'm not going to get into hypotheticals like that" - the congressman did emphasize that Romney will not back down from any budget fights.

"He's already there. He's already saying we have to offer the country the choice of two futures. We need serious leaders who are going to put out serious solutions and he wants to take this to the country," Ryan said.

To that end, Ryan said that Romney will defend his controversial budget during the upcoming campaign - and do so effectively.

"We're proud of our budget and we relish the debate about two futures," Ryan said. "Mitt Romney has already embraced these kinds of ideas with his own policy prescriptions, how to save Medicare, how to reform the tax system, how to cut spending, how to cap the growth of government. He's already been out front on these ideas. That's one of the reasons I endorsed him. I think he relishes this debate."

But first Romney has to secure the Republican presidential nomination once and for all. A victory in Wisconsin's primary Tuesday night would help.

"I've got a great feeling," Ryan said about Romney's chances in the Badger State. "The sense I'm getting is that conservatives are beginning to coalesce and focus on the fall. And I think most conservatives are making the same conclusion I made, which is that I think Romney is going to be the best president of the crowd and has the best chance of beating Obama in the fall.

"If we drag this on, it's going to be to our detriment," Ryan warned. "I do believe it's going to be very counter-productive if they keep on trying drag this thing out, which will make it that much harder for us to win in the fall."

Matthew Jaffe is covering the 2012 campaign for ABC News and Univision.