Hillary Clinton still tops Chris Christie in Iowa

Former Secretary of State Hillary Clinton holds a baby at an event promoting her new book, "Hard Choices: A Memoir," on the campus of George Washington University June 13, 2014, in Washington, D.C.

Chip Somodevilla, Getty Images

In the swing state of Iowa, former Secretary of State Hillary Clinton still enjoys a comfortable lead over New Jersey Gov. Chris Christie in a theoretical presidential match-up, according to a new survey.

Clinton leads Christie 44 percent to 36 percent, according to the Quinnipiac poll, conducted June 12-16. The poll has a 2.7 percent margin of error. The survey shows that Christie's public approval rating has yet to recover from the scandal over lane closures on the George Washington Bridge. Before that scandal broke in January, Quinnipiac found that Christie was ahead of Clinton in Iowa. Still, Christie's current status against Clinton has improved marginally since Quinnipiac's March survey.

Among independent voters, Clinton has a 10-point lead over Christie (41 percent to 31 percent).

While his public image recuperates in the wake of the bridge scandal, Christie has been laying the groundwork for a presidential campaign. Recently, he spoke to religious conservatives in Washington and visited the early-nominating state of New Hampshire.

Three other potential Republican 2016 contenders fare slightly better against Clinton, who has yet to announce her intention to run for the Democratic nomination: Clinton tops Sen. Rand Paul, R-Ky., 46 percent to 40 percent, while she leads Rep. Paul Ryan, R-Wis., 47 percent to 41 percent. She bests former Arkansas Gov. Mike Huckabee 46 percent to 39 percent. The former secretary of state has a larger lead against former Florida Gov. Jeb Bush, at 49 percent to 36 percent.