Sen. Mark Kirk was officially sworn in Monday, handing Republicans another vote in time for the crucial days of the lame-duck session.

Kirk won the Senate seat previously held by President Barack Obama in Illinois and is the third of three new Senators to join the chamber during the lame-duck session. The former House Member won both his own six-year Senate term and a special election to replace appointed Sen. Roland Burris (D-Ill.) for the remainder of this year. He resigned his House seat Monday to move across the Capitol.

A fiscal hawk, Kirk takes his seat just as Members prepare to debate how to extend expiring tax cuts enacted President George W. Bush and a continuing resolution or omnibus spending bill to keep the government funded next year. An appropriator in the House, Kirk is an opponent of earmarks and has said he will oppose any Senate omnibus measure laced with funding for special projects. Kirk also penned an editorial Monday in the Chicago Tribune in which he called on the Senate to adopt a moratorium on earmarks. The newly minted Member will get his chance to push that cause later Monday evening when the Senate considers an amendment sponsored by Sen. Tom Coburn (R-Okla.) to adopt such a moratorium.

While Kirk may not cross party lines on those issues, the social moderate could vote with Democrats on social policies, including upcoming votes on the DREAM Act and a repeal of “don’t ask, don’t tell.” In the House, Kirk supported enforcement against gay hate crimes but opposed repealing the policy on gays in the military.

The other two Senators who have already been sworn in are Democrats ­— Chris Coons of Delaware and Joe Manchin of West Virginia.

Editor’s Note

An advance version of this story was mistakenly posted earlier Monday.