President Obama  will try to reshape Washington’s debate over the nation’s fiscal crisis on Wednesday with a speech outlining his approach to tackling the debt and the long-term health of entitlement programs, while navigating the tricky politics that will confront him as he seeks re-election.

Mr. Obama has until now largely ceded the task of confronting the nation’s biggest fiscal challenges, first to his own debt commission and more recently to House Republicans, who last week proposed a plan that would remake Medicare and Medicaid while slashing $6 trillion in spending over the next 10 years.

But White House aides said Tuesday night that in the speech, the president will lay out his own, four-part plan to deal with the growing deficit and the reality that the costs of entitlement programs are growing rapidly.

“The President’s proposal will build off of the deficit reduction measures included in his 2012 budget and will borrow from the recommendations of the bipartisan fiscal commission he created,” said a White House official, who offered guidance on background ahead of Mr. Obama’s speech.