[cnn-photo-caption image= http://i2.cdn.turner.com/cnn/2009/images/08/19/art.crist.0819.jpg caption="Crist holds on to primary lead as appointment questions linger."]
(CNN) - A new poll suggests Florida Gov. Charlie Crist is holding on to a clear advantage over his Republican primary opponent in next year's Senate race. But it's far from clear who he'll be facing – or replacing.
On Tuesday, GOP Rep. Lincoln Diaz-Balart declined a Crist invitation to submit a formal application for the seat being vacated by retiring Republican Sen. Mel Martinez, who is stepping down early. Several candidates reportedly remain in the running, including state Rep. Jennifer Carroll, who met with the governor Wednesday and plans to apply for the post. If Carroll were appointed, she would be the first black Republican woman to serve in the U.S. Senate, and the only African-American member of the GOP in the current Congress.
Crist - who continues to hold a sizeable cash advantage over the former speaker of the state's House of Representatives, Marco Rubio – is maintaining a similar edge in the Quinnipiac survey released Wednesday.
Fifty-five percent of Florida's registered Republicans said that they would back Crist in the GOP Senate primary – more than double the 26 percent behind Rubio, who's counting on strong support from a conservative base unhappy with the National Republican Senatorial Committee's early decision to back the governor's Senate bid. Eighteen percent remain undecided.
On the Democratic side, Rep. Kendrick Meek is holding on to a narrow edge in the race for the party's 2010 nod. Eighteen percent of the state's Democrats support Meek, with 12 percent backing Rep. Ron Klein, and 9 percent behind Rep. Corrine Brown. But a clear majority – 57 percent – of the state's Democrats have yet to choose a candidate.
The Quinnipiac poll of 1,136 Florida voters questioned by telephone was conducted August 12-17 has a sampling error of plus or minus 4.6 percent for the 446 Republican voters questioned and 4.7 percent for the 434 Democrats questioned.