Ledyard King

USA TODAY

It looks like Senate GOP leaders are right to push Sen. Marco Rubio to run for re-election.

A Quinnipiac University poll released Wednesday indicates the first-term Republican from West Miami is the only GOP candidate who would defeat either of the two big-name Democrats vying for the Senate seat, if the election were held today.

As a presidential candidate, Rubio pledged not to run for a second Senate term. But he's under mounting pressure from GOP leaders to run again for a seat that could determine whether Republicans maintain control of the Senate. They now occupy 54 of the 100 seats.

The Quinnipiac poll of Florida voters also looked at two other key states where GOP-held Senate seats are up for election this fall. And the news is good for Republicans.

In Ohio, GOP Sen. Rob Portman is now tied with former Democratic governor Ted Strickland, who once led by as many as 9 points.

And in Pennsylvania, Republican Sen. Pat Toomey is pulling away from Democratic challenger Katie McGinty 49% to 40% in a race that was a statistical tie only last month.

"It is far too early to say he’s a sure thing, but he is in good shape," Peter Brown, assistant director of the Quinnipiac poll, said of Toomey.

Political handicappers have rated all three races as tossups — and crucial to Democratic hopes of taking back the Senate.

Rubio's decision to seek re-election would be a dramatic boost for Republicans, the Quinnipiac poll suggests.

The two congressional Democrats running for the nomination — Alan Grayson of Orlando and Patrick Murphy of Jupiter — each win head-to-head against any of the four major Republican candidates, Rep. Ron DeSantis, Lt. Gov. Carlos Lopez-Cantera, and businessmen Todd Wilcox and Carlos Beruff.

Murphy leads each by at least 9 points, while Grayson would beat each by at least 5 points.

But Murphy would lose to Rubio by 7 points and Grayson would lose to him by 8 points if Rubio decides to run again, according to the poll. A number of GOP leaders, including Senate Majority Leader Mitch McConnell of Kentucky and presumptive GOP presidential nominee Donald Trump, have urged him to do just that.

“With Republican national leaders worried about keeping control of the U.S. Senate, Sen. Marco Rubio might ride to their rescue if he decides to reverse field and seek re-election,” Brown said.

Rubio has until noon Friday to file for re-election. Most expect he'll do so. GOP Rep. David Jolly opted out of the Senate race last week and filed for re-election, based on his assumption that Rubio will declare for a second term.

A recent poll by St. Leo University found Rubio would dominate the Aug. 30 GOP primary, winning 52% of the Republican vote.