Sen. Marco Rubio could be Hillary Clinton's biggest rival. The latest Quinnipiac University poll of swing states released Wednesday indicated that Rubio -- compared to other Republican presidential candidates -- appears to be a close contender to Clinton in Pennsylvania and his home state of Florida.

Clinton still outpaces Rubio in his home state but not by much. Clinton leads Rubio 47 percent to 44 percent with Florida voters in a hypothetical presidential matchup, according to the Quinnipiac poll. Former Florida Gov. Jeb Bush garnered 42 percent of the Florida vote, compared with Clinton's 46 percent in a similar hypothetical.   

"It's a long way until Election Day, but in the critical swing states of Florida, Ohio and Pennsylvania, U.S. Sen. Marco Rubio of Florida has a tiny edge over the GOP field, " said Peter A. Brown, assistant director of the Quinnipiac Poll, in a statement.

The matchup between Rubio and Clinton was even closer in Pennsylvania. Rubio edges Clinton by a 44 percent to 43 percent count. The poll found Sen. Rand Paul also held a very slight edge over Clinton in the state.

Perhaps Clinton's toughest challenge comes in Ohio, however, where Ohio Gov. John Kasich outpaced her 47 percent to 40 percent in a matchup. Clinton split a matchup -- 43 percent to 43 percent -- with Sen. Rand Paul in Ohio and managed to best the other Republican candidates. Rubio earned 42 percent of the vote in Ohio against Clinton's 45 percent.

The poll was conducted from June 4-15, and it surveyed 1,147 Florida voters, 1,191 Ohio voters and 970 Pennsylvania voters. The margin of error was plus-or-minus 3 percentage points in Florida, 2.8 percentage points in Ohio and 3.2 percentage points in Pennsylvania. 

The results of Rubio-Clinton matchup fall within the margin of error in both Florida and Pennsylvania, suggesting a tight race. Voters from the three swing states backed Clinton -- by a range of degrees -- over Bush, New Jersey Gov. Chris Christie, former Arkansas Gov. Mike Huckabee, Wisconsin Gov. Scott Walker and Sen. Ted Cruz. While Rubio might currently hold the best position among the GOP field in swing states, the results of the poll also indicate the rest of the field isn't too far behind.

"Most of the...GOP hopefuls are within striking distance of [former] Secretary Hillary Clinton in at least one of the three states," Brown said in a statement.

The worst news from the poll for Clinton might be that voters in all three states suggested she had not earned their trust. By a margin ranging from eight percentage points to 14 percentage points, voters in Florida, Pennsylvania and Ohio said that Clinton was not "honest or trustworthy."

“This is where Democrats almost always fare better than Republicans," said Brown in a statement. "Yet in this survey, many Republican candidates do as well or better than does she.”