 Another member of the U.S. Senate calling on the president to pass the torch. Fox's Jack Callahan. Ohio's Senator Sherrod Brown saying in a social media posting, I think the president should end his campaign. He becomes the fourth Senate Democrat to do so. Joining Montana's John Tester, New Mexico's Martin Heinrich and Vermont's Peter Welch. Of the four, only Senator Welch is not up for reelection this year.