Congress returns this week for a four-week stretch in which Democratic leaders hope for quick progress toward writing the 12 regular appropriations bills and will push ahead on sweeping global warming and health care legislation.

Behind the scenes, the Senate will prepare for confirmation hearings now expected in mid-July for Supreme Court nominee Sonia Sotomayor, whom President Obama wants confirmed before the Senate leaves for its long summer recess in early August.

In the House, Republicans have made no secret of their plans to continue hammering at Speaker Nancy Pelosi for her contention that CIA briefers misled her in 2002 about the use of waterboarding on terrorism suspects. So far, Democrats have remained united behind the Speaker. They say they won’t be distracted from moving what they describe as one of the most ambitious legislative agendas that Congress has tackled in decades.

“This is not a do-nothing Congress. We will not accept those who say the status quo is OK,” Rep. Xavier Becerra , D-Calif., the House Democratic Caucus vice chairman, said before Congress left for its Memorial Day break.

Perhaps nowhere is the congressional leadership’s determination to use big Democratic majorities in both houses to get work done expeditiously more on display than in the appropriations process. House and Senate leaders say they are optimistic that Congress can pass all 12 appropriations bills in regular order, negating the need for an omnibus spending bill for the first time since 2005.

The House’s goal is to pass all 12 bills before leaving for the August recess. The Senate traditionally acts after the House on spending bills, so Senate Appropriations Committee Chairman Daniel K. Inouye , D-Hawaii, has set a goal of Senate passage for all the bills by Sept. 30, the end of the 2009 fiscal year, Senate staff says.

Asked about the chances of avoiding an omnibus, Sen. Byron L. Dorgan , D-N.D., expressed “hope” it can be done. “I don’t think anybody has an appetite to do another omnibus this year,” said Dorgan, who chairs the Appropriations Energy and Water Subcommittee.

Rep. Robert B. Aderholt of Alabama, ranking Republican on the Legislative Branch Subcommittee, said it’s “too early to tell” if all 12 bills can be passed individually. He put the odds at 50-50.

House appropriations subcommittee markups of spending bills are expected to start as soon as the week of June 8 and continue for another two weeks, according to lawmakers and House leadership staff. The Senate Appropriations Committee plans to start subcommittee markups the third week of June.

In other legislation, one of the first bills the House and Senate might take up will be the conference report on the $96.7 billion supplemental spending bill (HR 2346) for the Iraq and Afghanistan wars. The biggest disputes are over $5 billion the Senate included for International Monetary Fund lending and $3.1 billion the House included for military aircraft procurement. Final action could come this week.

House Majority Leader Steny H. Hoyer of Maryland said that in coming weeks the House also will take up the Defense, State and Homeland Security departments’ authorization bills. Action also is expected on the conference report for legislation giving the Food and Drug Administration power to regulate tobacco (HR 1256).

Hoyer said he wants the controversial global warming bill (HR 2454) to pass the House “in the latter part of June or the early part of July.” But such rapid movement of a bill that the Energy and Commerce Committee passed on May 21 after weeks of wrangling among Democrats will depend on whether more than a half-dozen committees with jurisdiction over pieces of the bill either conduct markups or waive that right. And that is still up in the air.

In the Senate, where Democratic leaders are trying to reach as much of a consensus as possible before starting to write a climate change bill, committees are waiting for the final House product before starting the formal legislative process.