It's worth noting that Braun is doing something rare: seeking to become governor as a member of the U.S. Senate. In 2021, SmartPolitics found that just 21 sitting or former U.S. senators had been elected governor while 153 sitting or former governors had been elected or appointed to the Senate. This isn't necessarily surprising: After all, a senator has six-year terms and no term limits, while governors in 48 states have four-year terms (two years in New Hampshire and Vermont) and often do have term limits.
I took a look at the six sitting senators who ran for governor from 1990 to 2024, and I found that Braun's primary vote share (a little under 40 percent) is worse than any among this small group — in part because he arguably has more significant competition than the others faced, including Indiana's current lieutenant governor. The senator who won the lowest percentage prior to Braun was Republican Sen. Frank Murkowski, who won 70 percent in the 2002 GOP primary for Alaska's governorship. After Murkowski won that November, he became governor and appointed his daughter, Lisa Murkowski, to fill his vacant former Senate seat, which she still holds today. The elder Murkowski became extremely unpopular, however, and lost the 2006 GOP primary for governor to Sarah Palin, the former chair of the state's Oil and Gas Conservation Commission.
The other four sitting senators seeking the governorship in this period all won at least 80 percent in their primaries: Sens. Sam Brownback of Kansas (2010), Jon Corzine of New Jersey (2005), Dirk Kempthorne of Idaho (1998) and Pete Wilson of California (1990).
—Geoffrey Skelley, 538