WASHINGTON — The Democratic-dominated Congress convenes today to confront perhaps the worst economic crisis since the Great Depression and to grapple with a hugely ambitious agenda set by President-elect Barack Obama.

The opening day of a two-year session is typically more ceremony than substance, and Congress often recesses until the new president takes office or after the State of the Union address at the end of January.

This year, however, with the economy in a worsening recession, Democrats are promising swift action on an as-yet-unveiled $775 billion economy recovery program that is the first order of business for the Obama administration.

“We will hit the ground running ... to address the pain being felt by the American people,” House Speaker Nancy Pelosi, D-Calif., promised Monday as she welcomed Obama to her office.

For the first time in 16 years, Democrats control both houses of Congress and welcome one of their own to the White House. That foreshadows a productive session, particularly if Obama can muster Republican support for his initiatives, as he is seeking.

Pelosi had earlier promised to try to get the economic recovery bill ready for Obama’s signature by Inauguration Day, an optimistic timeline that has now slipped by several weeks.

With their numbers bolstered by last fall’s elections, congressional Democrats are well-positioned to dominate the session.

Democrat Al Franken on Monday became the apparent victor in a hard-fought Minnesota Senate race. That means Democrats’ numbers in the chamber could reach 59 — tantalizingly close to the magic 60 votes needed to overcome a GOP filibuster. Incumbent Republican Norm Coleman promises to contest the result.

But first, Senate Democratic leaders need to work out a looming confrontation with Roland Burris, the Illinois Democrat named by scandal-plagued Gov. Rod Blagojevich, who faces charges of having attempted to sell the seat.

Burris, who is black, came to Washington on Monday to claim the seat, though Democratic officials promise he won’t be admitted to the Senate carrying the taint of Blagojevich.

In the House, Pelosi finds her own position strengthened by a gain of more than 20 seats. Her status as the top Democrat in Washington, however, has been supplanted by Obama.

The Democratic majority will be 256 to 178 with one vacancy when the new House is sworn in, compared to 235-198 with two vacancies at the end of the previous Congress.

Democrats will use their bolstered majority to push through several changes to House rules, including a repeal of the six-year term limit for committee chairmen.

That rule was imposed when Republicans seized control of Congress in 1995, after decades in which autocratic chairmen dominated the House. That era is mostly over, however, with power concentrated in Pelosi’s office.

For Republicans, the next two years promise to be difficult. They vow to work with Obama but at the same time have installed a more conservative leadership team.

 in the House that’s eager to draw distinctions with Democrats.

In addition to the economic recovery plan, early items on the agenda include a measure designed to ensure women have the right to sue their employers for pay discrimination. It passed the House but fell prey to a GOP filibuster in the Senate. Now it looks as though it will easily pass.

Despite the sense of optimism, however, troubling realities threaten the Democratic agenda.

Perhaps most dangerous is the spiraling budget deficit. On Wednesday, lawmakers will get some very sobering news: New budget deficit projections from congressional estimators project a flood of red ink — likely to exceed $1 trillion for the current budget year — that could threaten other initiatives like extending health care to millions of the uninsured.

With that in mind, Obama promises “very concrete, serious plans for midterm and long-term fiscal discipline.”