Washington ? For senators with presidential aspirations, 2007 looms like a potential minefield.

The schedule alone is a career-enhancement hazard.

When Congress returns under Democratic control in the first week in January, the House and Senate will be tied up with spending bills and other legislation left over from this year, plus an ambitious agenda set by new Democratic leaders.

Lawmaking will be a balancing act between voters’ expectations and legislative pragmatism, between the impulse to spend and fiscal discipline, between campaigning and staying in Washington to govern.

The likely candidates next year face votes on appropriations, budgets and trade – all of which present potential pitfalls in a presidential campaign.

Congress also could consider immigration and Social Security legislation, two issues that attract widespread public interest as well as alarm. Hanging over all that will be Iraq.

So far six Democratic and three Republican senators are weighing whether to run for president in 2008. Two House Republicans also are in the mix. The race is off to an early start, with potential candidates setting up their campaign and fundraising operations and seeking early media exposure.

For the Democrats in particular, that amounts to serious multitasking.

At least three – Sens. Joe Biden of Delaware, Christopher Dodd of Connecticut and John Kerry of Massachusetts – will be committee chairmen in the Senate. Two other senators – Hillary Rodham Clinton of New York and Evan Bayh of Indiana – are in line to head two subcommittees, where much legislation originates.

Senate Democratic leader Harry Reid of Nevada has pledged to increase the work tempo in the Senate, promising votes throughout the week instead of the current Tuesday to Thursday schedule.

“It’s going to be interesting to see if those folks who are in the Senate and who now have the responsibility to chair committees, to sort of run the show, whether their attention will be captured by the Senate or whether they will make time to come campaign,” said Dick Harpootlian, a former chairman of the Democratic Party in South Carolina. His state is a requisite stop early in the presidential sweepstakes.

As senators, Republican and Democratic presidential contenders will face difficult choices on the Senate floor. Democrats have pledged to budget frugally, spending or cutting taxes only if the money can be made up elsewhere.

That is a tall order given their desire to increase spending on education and fix the alternative minimum tax, intended to ensure the wealthy do not avoid taxes through loopholes.

Congress also will have to address nettlesome trade issues.