President Obama will embark on a three-day blitz of Capitol Hill starting Tuesday, his latest stab at a "grand bargain" that would curtail runaway deficits and put an end to the stopgap style of governing that has brought his agenda to a grinding halt.

The White House is framing Obama's rare venture to the other end of Pennsylvania Avenue as an attempt to secure a "bipartisan agreement on deficit reduction that couples entitlement reform with tax reform."

Obama would like to put behind him looming fiscal debates, like the temporary spending measure needed to keep the government open after April 1 and the increase in the nation's borrowing limit to avoid default. Doing so would allow Obama to focus on immigration and gun control, among other contentious issues, that are being overshadowed by fiscal clashes.

But it's not that simple. Here are the major barriers to the type of deal that has eluded Obama and congressional leaders:

• Tax reform

When Obama talks taxes, it's usually about eliminating loopholes for corporate jet owners and oil companies -- relatively small provisions that would hardly put a dent in soaring deficits.

Republicans say they're done talking about higher taxes, particularly after agreeing to raise rates earlier on those earning $400,000 or more a year. If Obama has any hopes of extracting a deal from conservatives, he must explore a broader overhaul of the tax code, one which would lower corporate rates, among other levies, Republicans said.

"Obama cherry-picks a handful of taxes when it's the whole code that is out of sync," said former Rep. Bob Walker, R-Pa. "If all we're going to do is play silly games, call for 'taxing the rich,' there is no chance for a deal."

• Entitlements

Republicans accused Obama of backtracking from past commitments to curtail entitlement programs. And ahead of Obama's trek to Capitol Hill, the White House reiterated that the president had no interest in raising the Medicare eligibility age, as Republicans recommend.

Obama suggested he's open to changes in Social Security and Medicare to reduce costs but lambasted a Republican proposal to revamp Medicare as a "premium support" program that would give beneficiaries money to buy private insurance.

"Entitlements are the endgame," said a senior Republican leadership aide. "We're wary he'll take on his base, but that's the silver bullet. If the president shows us that he's serious, that could open the floodgates."

• Competing budget plans

Obama is arriving on Capitol Hill just as the Republican-led House and democratically-controlled Senate are unveiling their own budget proposals, though neither of those proposals are likely to include all that Obama wants. The House plan, for instance, would cut all spending on Obama's signature health care reforms.

Republicans are pushing for substantial spending cuts that would help balance the budget within 10 years, but White House spokesman Jay Carney said Monday that Obama is more interested in growing the economy than balancing the budget.