The latest poll of Florida voters shows that the contest to replace Sen. Marco Rubio (R-FL) in the United States Senate is wide open, for both Republicans and Democrats, with several viable contenders and a large percentage of undecided voters on both sides.

The poll was conducted by Mason-Dixon Polling & Research, Inc. from July 20 through July 24, 2015 of 500 registered Republican voters and 500 registered Democratic voters statewide in Florida using landlines and cell phones. The margin of error was +/- 4.5 percent.

“Both primary races at the present time are muddled to say the least,” wrote Mason-Dixon Managing Director J. Bradford Coker in the poll analysis, noting that the entire field of currently declared or expected candidates were polling fairly close together, and no one could legitimately claim to be a “front-runner.”

With Florida’s August 2016 primary still more than a year away, it would be highly unlikely for any candidate to have the race sewn up already, but this poll does settle some questions about how the race would be affected if some of the potential candidates jumped in: former Attorney General Bill McCollum (R-FL) and Rep. Gwen Graham (D-FL).

Both Graham, the daughter of former Florida Gov. Bob Graham, and McCollum, who also represented a Central Florida district in Congress and has run statewide before (albeit unsuccessfully), have a foundation of name recognition that would be expected to make them contenders, but this poll shows that their entry would not significantly shake up the race.

Mason-Dixon questioned Republican respondents both with and without McCollum in the race, and Democrats with and without Graham.

Among Republicans and including McCollum, McCollum had 22 percent support, Rep. David Jolly (R-FL) had 11 percent, Rep. Ron DeSantis (R-FL) had 8 percent, Lt. Gov. Carlos Lopez-Cantera (R-FL) had 7 percent, Rep. Jeff Miller (R-FL) had 6 percent, and Army veteran and businessman Todd Wilcox had 1 percent. Almost half of the respondents — 45 percent — were undecided.

If McCollum is omitted, than 16 percent of Florida Republicans supported Jolly, 10 percent for Lopez-Cantera, 9 percent for DeSantis, 8 percent for Miller, 2 percent for Wilcox, and an even larger number — 55 percent — were undecided.

McCollum is in the lead, but not by a very large margin, especially with so many undecided voters. Also, his track record in statewide races is largely negative, losing Senate races in 2000 and 2004, winning the 2006 Attorney General election, and then losing the 2010 Republican nomination for Governor to Rick Scott. “Given his history of losing early leads in several previous statewide races, that number [22 percent support] would not be daunting enough to scare away any rivals,” wrote Coker.

Graham is less of a factor for the Democrats, coming in third place. When her name is included, Rep. Patrick Murphy (D-FL) gets 26 percent of the vote, Rep. Alan Grayson (D-FL) gets 24 percent, Graham 11 percent, and 39 percent undecided. If Graham is not included, then Grayson has a slim lead at 33 percent to Murphy’s 32 percent, and 35 percent undecided.

Follow Sarah Rumpf on Twitter @rumpfshaker.