Deirdre Shesgreen

USA TODAY

Battleground Senate races in Ohio, Pennsylvania and Florida are all close, a new Quinnipiac University poll shows.

The poll found that 43% of Ohio voters support former Democratic Gov. Ted Strickland and 42% support Republican Sen. Rob Portman — a dead heat, and virtually unchanged from the last two Quinnipiac polls, in February and October.

In Florida, the race to replace Florida Sen. Marco Rubio remains wide open, with five Republicans and two Democrats competing ahead of that state's Aug. 30 primary. Rep. Patrick Murphy does better than fellow Democrat Alan Grayson against several Republican challengers, but roughly a third of the electorate remains undecided.

Rubio, who got trounced by Donald Trump in Florida’s March 15 presidential primary, still doesn’t resonate highly in his home state. He has a negative 42%-49% approval rating, compared to fellow Sen. Bill Nelson, D-Fla., who gets a positive 47%-26% score.

In Pennsylvania, Republican Sen. Pat Toomey has 45%, while Democratic challenger Katie McGinty has 44%.

Quinnipiac conducted the poll of 1,042 Ohio registered voters from April 27 through Sunday.

The university surveyed 1,051 registered voters in Florida and 1,077 in Pennsylvania, two other battleground states where voters will help determine which party controls the Senate in 2017.

The margin of error for all three state polls was 3 percentage points.

In Ohio, the poll reaffirmed that Portman’s biggest liability is his low name recognition, with 42% of Ohioans saying they don't know enough about the Ohio Republican to have an opinion.

The poll also showed a majority of registered Ohio voters say the Senate should take up President Obama's nomination of Merrick Garland to fill the Supreme Court vacancy, with 56% of Buckeye State voters wanting action compared to 38% who support the GOP’s refusal to hold hearings or a vote on Garland.

Garland’s nomination has become a political football in Ohio’s Senate race, with Democrats blasting Portman almost daily for his decision to block a confirmation vote on Garland.

Like other Senate Republicans, Portman has said the next president should fill the vacancy left by Justice Antonin Scalia’s sudden death in February. Strickland says Portman is being obstructionist and “abandoning his constitutional duties.”

Wednesday’s poll is likely to further fuel Strickland’s line of attack. But the poll also showed that nothing seems to be moving the needle in that Senate contest — not the Supreme Court vacancy, not the boisterous White House race, not the piles of campaign cash already spent.

Other key findings in Ohio:

• Gov. John Kasich’s presidential bid did not do serious damage to his favorability ratings at home. Ohio voters approve of the job Kasich is doing by 58% to 32%.

• Sen. Sherrod Brown, D-Ohio, wins a 46% job approval rating in the poll, something Democratic presidential front-runner Hillary Clinton may consider as she decides whether to vet the senator as a vice presidential candidate.

• Buckeye state voters overwhelmingly support legalizing medical marijuana by a margin of 90% to 9%. They narrowly support allowing recreational use of the drug, by 52% to 45%.

Contributing: USA TODAY reporter Ledyard King.