House Budget Committee Chairman Paul Ryan says the budget he will unveil this week counts on a repeal of President Barack Obama's signature health reform law, a position which is unacceptable to many Democrats and unlikely to become law.

Asked on "Fox News Sunday" about the political reality that a repeal of Obamacare is unlikely, Ryan responded, "Well, we believe it should, that's the point. That's what budgeting is all about. ... It's about making tough choices to fix our country's problems. We believe that Obamacare is a program that will not work."

The Wisconsin Republican has taken aim at the program in previous budget proposals and on the 2012 campaign trail as the GOP vice presidential nominee.

While he supports the overturn of that program, Ryan factored another of the president's policy successes into his budget: the tax increases Democrats included in the fiscal cliff deal back in January. At the time, Republicans argued against the increases, saying they would hurt employment, small businesses and the broader economy.

"The new baseline reflects the fiscal cliff, which is higher revenues, and lower spending, making it easier to balance," he said. "We don't want to refight the fiscal cliff. That's current law. That's not going to change."

The added revenue means Ryan's budget would eliminate the federal deficit in 10 years. Previous House GOP budgets have projected that it would take 25 years to balance the budget.

Ryan said his budget will increase federal spending on average 3.4% each year over the 10-year period, but that is $5 trillion less than the current 4.9% rate of federal government growth over the period, he said.

His plan would include the forced spending cuts known as the sequester, which became law under the 2011 Budget Control Act, but only for the next two years. Those cuts were implemented at the beginning of this month and amount to $85 billion this year and a total of $1.2 trillion over the decade. Ryan proposed eliminating those cuts to defense programs in his budget last year. Republicans have supported overriding the sequester's broad cuts to defense and giving the Obama administration discretion to choose how to save the sum of money.

Ryan gave reporters a preview of his budget on Wednesday and is expected to release it this week.

At the same time, he backed off a proposal to make changes to Medicare for people under the age of 57. He and other Republicans have repeatedly said their proposals would not change the program for people over the age of 55, and setting the bar at 57 could open him to political criticism. GOP aides said an analysis of the two-year difference showed it would not save the federal government a significant amount of money.

"This guarantees that Medicare does not change for people in or near retirement, and it also guarantees for those of us who are under the age of 55 that we actually have a Medicare program when we retire," Ryan said on Sunday.

Ryan proposes replacing the current system with a traditional Medicare option alongside other options. Seniors would receive support from the government toward paying their premium based on their income level and health, he has indicated.

Democrats generally do not support such a model. Ryan disputed that his party was hurt by the issue in the presidential campaign, saying, "We won the senior vote. I did dozens of Medicare town hall meetings in states like Florida, explaining how these are the best reforms to save and strengthen the Medicare program, and we're very confident that this is the way to go."

Ryan, who met last week with Obama, said on Fox the prospects of the president and congressional Republicans working together will be "based on how he conducts himself in the coming weeks and months."

"This is the first time I've ever had a conversation with the president that lasted more than two minutes or televised exchanges. So I've never really had a conversation with him on these issues before," he said, saying he was "excited" that this "frank" conversation over lunch took place.

"Will he resume the campaign mode? Will he resume attacking Republicans and impugning our motives? Will he resume what is long believed to be a plan to win the 2014 elections? Or will he sincerely change and try and find common ground, try and work with Republicans to get something done? That's what we hope happens," Ryan added.

This week, Obama is scheduled to speak to members of both parties on Capitol Hill.

As to his own interest in running for the White House, Ryan said his vice presidential bid was "a very positive experience" and "made it (a White House run) more realistic in my mind -- it's something that I much better understand."

He signaled that a bid for the presidency would be more likely than a run for top legislative positions, saying, "If I wanted to be in elected leadership, like speaker, I would have run for these jobs years ago."