A day before delivering a pivotal speech on the need for health care reform, President Barack Obama on Tuesday reaffirmed his commitment to a comprehensive overhaul and pointed to specific GOP ideas that he is open to including in his final blueprint.

Obama said in a letter to Congressional leaders that he left last week’s bipartisan health care summit “convinced” that both parties “have more in common than most people think.” He pointed to common ground on insurance reforms and on the need to rid Medicare of waste, fraud and abuse.

The president said he is also exploring four GOP ideas for inclusion in his final proposal: private investigations by medical professionals to reduce fraud and abuse, providing funds to help states launch tort reform demonstrations, increasing doctors’ Medicaid reimbursements and expanding health savings accounts.

Obama also knocked down the Republican talking point that health care reform should be done in a piecemeal manner. This approach “is not the best way to effectively reduce premiums, end the exclusion of people with pre-existing conditions or offer Americans the security of knowing that they will never lose coverage,” he said.

Obama’s letter to Speaker Nancy Pelosi (D-Calif.), Senate Majority Leader Harry Reid (D-Nev.), Senate Minority Leader Mitch McConnell (R-Ky.) and House Minority Leader John Boehner (R-Ohio) comes a day before the president is set to announce what his final health care proposal will look like — and how he wants Congress to pass it.

Obama will discuss both the “process and policy” of his plan during a speech somewhere in the Washington, D.C., area, White House Press Secretary Robert Gibbs said Monday.

Gibbs said Obama will post his revised plan on the White House Web site; the plan will not be legislative language but instead a “broad outline” of how Obama envisions a final bill.