Iowa Republican Senate nominee Joni Ernst is returning to a theme that helped her make a splash on the national political scene: hogs.

In a new TV ad out Wednesday, Ernst is on a farm surrounded by hogs as she draws parallels to Congress.

"It's a mess," Ernst says in the 30-second ad. "Dirty, noisy and it stinks. Not this lot. I'm talking about the one in Washington."

Polls suggest Ernst is in a very close race against Rep. Bruce Braley (D). Iowa is one of about a dozen races that could determine which party controls the Senate in 2015.

In March, Ernst released an ad in which she said, "I grew up castrating hogs on an Iowa farm. So when I get to Washington, I'll know how to cut pork." At the end of that ad Ernst concluded, "Washington's full of big spenders. Let's make 'em squeal."

Republican U.S. Senate candidate Joni Ernst (R) of Iowa has released a new TV ad saying she'll know how to cut pork in Washington. (YouTube: Joni Ernst)

The spot went viral and helped introduce Ernst at a time when she was not well-known. She went on to coast to victory in the Republican primary.

In her newest ad, Ernst concludes, "Cleaning up the mess in Washington is going to take a whole lot of Iowa common sense."