WASHINGTON -- Tennessee's senior senator, Lamar Alexander, has jumped into the race to be the second-most powerful Republican in the Senate, according to one of his aides.

The position -- formally called the minority whip -- is opening up with announcement from Sen. Jon Kyl, R-Ariz., that he won't seek re-election in 2012.

Since 2008, Alexander has been the third-ranked Republican in the Senate. In 2006, he came within one vote of beating Sen. Trent Lott, R-Miss., for the No. 2 spot.

Besides trying to corral his fellow colleagues to vote with the party's position on pending legislation, the whip is in charge of counting votes in the GOP conference so the party has more power in negotiations with its Democratic counterparts.