Obama has been hoping to secure a large bipartisan majority for the stimulus package in congress to register a major political success in the symbolic first 100 days of his administration.
But some Republicans have doubts over the size and focus of the package, with John Boehner, leader of the Republicans in the house of representatives, saying many in his party remained concerned about the sheer size of the plan financially.
"I think at this point, we believe that spending nearly a trillion dollars is really more than what we ought to be putting on the backs of our kids and their kids, because at the end of the day, this is not our money to spend," he said.
"We're borrowing this money from our kids and so, we have to find a package that's the right size."
Obama said he "recognised" the differences between the administration and members of congress about "particular details" on the plan.
Obama also warned that the second half of a $700bn bailout of financial firms being debated in congress must ensure more accountability than that implemented by the Bush administration.
He mentioned recent press reports which said some Wall Street executives at companies that had received public bailout money had recently upgraded offices and private bathrooms.
He said politicians must "put in place the kinds of reform elements, oversight, transparency, accountability, that's going to be required in order for the American people to have confidence in what we're doing".
Obama was flanked as he spoke by Nancy Pelosi, the speaker of the House of Representatives, John Boehner, the senior Republican in the House, Harry Reid, the Senate Democratic leader and Mitch McConnell, his Republican counterpart.
Obama's comments came a day after Timothy Geithner, the US Treasury secretary-designate, vowed to reform the US financial system to make it stronger and more able to withstand world market turmoil.