By Richard Cowan and Susan Cornwell

WASHINGTON, Feb 11 (Reuters) - Congressional negotiators and White House officials met behind closed doors late on Tuesday to try to work out disagreements over spending and tax cuts in an economic stimulus bill that could cost taxpayers around $800 billion.

With President Barack Obama setting a weekend deadline for finishing the complex legislation -- and lawmakers hoping to start a week-long recess then -- the pressure was on to cut deals that would open the way for the Senate and House of Representatives to pass a final compromise.

"We're not there, but we've made a significant amount of progress the last 10 hours," Senate Majority Leader Harry Reid told reporters after he wrapped up Tuesday's final negotiating session.

Reid, a Nevada Democrat, said he hoped an agreement could be reached on Wednesday, but declined to detail the progress made.

White House Chief of Staff Rahm Emanuel, a former congressman, joined the discussions on Capitol Hill.

Obama met at the White House with fiscally conservative House Democrats, who told reporters they had received assurances that the administration would work to rein in future spending.

House Speaker Nancy Pelosi, a California Democrat, said she hoped all work could be done by the weekend, but noted that some House Democrats were "concerned" about Senate cuts to education and other spending initiatives already approved by the House.

According to one House Democratic aide, the negotiators might be able to come to a quick agreement on the tax-cut part of the bill, but the spending priorities could be more complicated.