(CNN) - It's pretty much all tied up in a crucial Senate contest that could decide whether the Republicans take control of the chamber in November's midterm elections, according to a new poll.
A Quinnipiac University survey of Iowa voters released Wednesday indicates Democratic Rep. Bruce Braley with a slight 44%-40% edge over GOP state Sen. Joni Ernst in the battle to succeed longtime Democratic Sen. Tom Harkin, who is retiring at the end of the year. If the Republicans can flip Harkin's seat and five other Democratic held seats, they would win control of the Senate.
Braley's four percentage point margin is within the poll's sampling error.
The close race compares to a 42%-29% Braley held over Ernst in a Quinnipiac survey from mid March. That right around the time that Ernst went up with her first campaign commercial, in which the candidate said "I'm Joni Ernst. I grew up castrating hogs on an Iowa farm so when I get to Washington, I'll know how to cut pork."
The provocative spot quickly gave statewide and even national attention to the little known state senator. It was followed by another ad that showed Ernst, a lieutenant colonel in the Iowa National Guard, riding up to a gun range on a motorcycle.
The commercials put Ernst in the spotlight and arguably helped turn her into the front runner in the free-for-all multi-candidate battle for the GOP Senate nomination. Ernst won the backing from both mainstream GOP organizations as well as anti-establishment and tea party groups, and ended up winning the June 3 primary by a landslide.
Braley, a four-term congressman, was unopposed in his primary.
Gender gap in spotlight
Ernst hopes to make history in November as the first woman to represent Iowa in Congress. But the poll indicates women backing Braley 47%-36% with men supporting Ernst 44%-40%. While it may seem unusual that women are backing the male candidate and the female candidate has a slight edge among men, remember that women voters tend to lean Democratic with men usually leaning towards the GOP.
Iowa voters give both candidates positive grades for character.
"Braley has a small lead in more measurements of personal characteristics and which candidate is better able to handle issues facing the state, but neither candidate's views and values are firmly fixed in the electorate's mind with a third of voters not knowing enough about either candidate to have an opinion," said Quinnipiac Poll assistant director Peter Brown.
"One interesting data point is that voters think 44 – 31 percent that Ernst cares about their needs and problems, a category in which Republicans, even victorious ones, often struggle. Her TV ads which stressed her farm family background apparently are doing their job," Brown added.
The Quinnipiac University poll was conducted June 12-16, with 1,277 Iowa voters questioned by telephone. The survey's overall sampling error is plus or minus 2.7 percentage points.