In the wake of last Tuesday’s election that may have seen the beginning of a GOP comeback, fueled (at least in part) by an energized conservative base, one of the next battles is gaining focus with a key endorsement today. Florida’s US Senate race to replace Republican Senator Mel Martinez who stepped down early is shaping up to be an extension of the battle between establishment GOP forces in Washington and the grassroots members of their party. Those grassroots Republicans in Florida were angered by the quick backing of moderate Governor Charlie Christ in over conservative rock star Marco Rubio, the state’s former House Speaker. Today, the conservative group, Club for Growth has officially endorsed Rubio over Crist in what is sure to be the fiercest intra-party skirmish of all the 2010 Senate races.

The Club’s endorsement is not a little one, as the organization managed to drive more than $400,000 to Conservative Doug Hoffman in his close loss in NY-23 last Tuesday. That was a race short on prep time where the group had little more than a several weeks to make an impact, here in Florida they’ll have a little more than eight months. Although the Club’s backing of Rubio is not really a surprise it is a great momentum bump for the conservative candidate who raised more than $1,000,000 between July 1st and September 30th for his primary challenge with Crist.

Look for the Club for Growth to throw some serious cash behind Rubio in the coming months for grassroots outreach, mail pieces, and most importantly – advertising.

In a race as high profile as the Rubio-Crist fight, the amount of money the Club will be able to raise is sure to be amplified significantly. By way of comparison, the Club raised former Rep. Pat Toomey (R) more than $1 million for his near-miss primary challenge to then Republican Sen. Arlen Specter in 2004. The Club helped raised in excess of $1 million for the candidacies of Sens. Jim Demint (R-S.C.) and Tom Coburn (R-Okla.) that same year and, according to those close to the Club, it has grown far larger and better organized in the ensuing years.

In a state such as Florida with multiple high-priced media markets, funding for TV and radio ads is key to a winning campaign. The Club will probably focus its ad buys on drawing attention to Crist’s breaks from the Florida GOP, most famously, his embrace of Barack Obama and his stimulus program. The White House said just recently (much to Crist’s dismay) that the Florida Governor has been “very supportive” of the President’s efforts. Be ready for that to be splashed all over the TV and radio.

With the close race in NY-23 last week, conservative activist efforts will be trained on several key 2010 races, and this battle between Rubio and Crist is sure to be one of them. The Club’s backing is only going to fuel the conservative fire among activists looking to show the national GOP that they cannot forget the wishes of the grassroots when working to get candidates elected to represent them in Washington.