MILWAUKEE -- Iowa Gov. Terry Branstad (R) said Saturday he is "particularly intrigued" by state Sen. Joni Ernst, a Republican candidate for U.S. Senate.

"We do have, I think, some fairly attractive candidates. I'm particularly intrigued by Joni Ernst," Branstad said in an interview at the National Governors Association meeting.

Branstad said he expects a "wide open race" and is "probably" not going to endorse a candidate in the primary. But he listed off several reasons why he thinks Ernst is a solid choice.

"She's pro-life, she's great on the second amendment, and she's been a very successful county official and now state senator," said Branstad, who later added, "She's got a great personal story. And we've never elected a woman to the Senate from our state."

The race for retiring Democratic Sen. Tom Harkin's seat features a tale of two primaries. On the Democratic side, Rep. Bruce Braley is expected to have an unobstructed path to the nomination. The Republican field is crowded, with no clear frontrunner. In addition to Ernst, the field includes David Young, a former chief of staff to Sen. Charles E. Grassley (R-Iowa); former U.S. attorney Matt Whitaker; and former conservative radio host Sam Clovis. Retired energy company chief executive Mark Jacobs has moved toward a run, as well.