Former Rep. Christopher Shays, a prominent GOP moderate who lost re-election in 2008, is preparing to enter the race for retiring Sen. Joe Lieberman’s (I-Conn.) seat.

A source close to Shays confirmed that the former 10-term lawmaker is in the process of hiring staff and interviewing consultants for his campaign team. The source added that Shays plans to campaign for Senate as a full-time job through the GOP primary next August.

The primary will be a tough test for Shays. Republicans say he’ll likely face Linda McMahon, the wealthy former CEO of World Wrestling Entertainment who poured $50 million of her own money into the 2010 Senate race before losing to now-Sen. Richard Blumenthal (D) by double digits.

Former U.S. Comptroller General David Walker, former Rep. Rob Simmons and Vernon Mayor Jason McCoy are also considering running for the GOP Senate nomination, although none appears close to entering the race. Lawyer Brian Hill already announced his candidacy for Senate this year.

Republicans have a tough task next year to compete in the Nutmeg State, especially in a presidential cycle. Roll Call rates this race as Likely Democratic.

Shays’ House campaign still carries more than $280,000 in debt from his 2008 loss to now-Rep. Jim Himes (D), according to his Federal Election Commission report. Most of that debt is from legal expenses related to battling his former campaign manager, who was sent to prison for embezzlement last year.