(CNN) - Hillary Clinton and Chris Christie are dead even in the key battleground state of Iowa in a hypothetical 2016 presidential showdown, according to a new poll.
A Quinnipiac University survey of Iowa voters also indicates that President Barack Obama's approval rating among Iowa voters has edged down since May. And according to the poll, which was released Monday morning, Hawkeye State voters are divided on the recent Supreme Court rulings on same-sex marriage.
In a possible 2016 White House matchup, 41% of Iowa voters say they would back Clinton, the former secretary of state, 2008 presidential candidate, U.S. senator, and first lady, if she were the Democratic nominee, with an equal amount saying they would back New Jersey Gov. Christie if he were the GOP nominee. In a hypothetical general election showdown with Wisconsin Gov. Scott Walker, Clinton has a 46%-39% edge.
Christie's on top 49%-32% when matched up against Vice President Joe Biden, with Walker edging Biden 42%-39%, in possible showdowns.
According to the poll, Clinton has a 52%-41% favorable/unfavorable rating with Iowa voters. Christie stands at 42%-16%, with the vice president at 38%-47% and nearly two-thirds saying they don't know enough about the Wisconsin governor to form an opinion.
"Christie's favorability ratio of almost 3-1 is impressive. The question is whether he can sustain it as he becomes better known," said Peter Brown, assistant director of the Quinnipiac University Polling Institute. "If so, he could be a strong contender in 2016."
Clinton, Biden, Christie and Walker are all considered possible 2016 White House contenders.
Besides being the first state to vote in the presidential caucus and primary calendar, Iowa is also a crucial battleground state in the general election.
As for the current president, Obama's approval rating stands at 41%, with 55% of Iowa voters saying they disapprove of the job he's doing in office. The 41% approval rating is down four percentage points from a May Quinnipiac poll, with the president's disapproval rating up five points.
On the issue of same-sex marriage, the poll indicates that 47% of Iowa voters support the rulings last month by the Supreme Court, with 44% opposed. The high court struck down part of the 1996 Defense of Marriage Act (DOMA), which denied hundreds of federal benefits to same-sex couples. But the justices declined to make a sweeping statement on the broader issue of same-sex marriage rights nationwide, rejecting California's same-sex marriage ban but leaving in place laws banning such marriages in 35 other states.
By a 55%-36% percent margin, Iowans oppose amending the state constitution to ban same-sex marriage. Iowans said by 57%-31% percent that such a ban would be struck down by the courts.
Same sex marriage became legal in Iowa following a 2009 decision by the state supreme court. Three state supreme court justices who ruled in favor of same-sex marriage were voted out of office in the 2010 elections. A state constitutional amendment to ban same-sex marriage has been proposed several times in the legislature.
The Quinnipiac University poll was conducted July 15-17, with 1,256 registered voters in Iowa questioned by telephone. The survey's overall sampling error is plus or minus 2.8 percentage points.
- CNN Political Editor Paul Steinhauser contributed to this report.