Wisconsin Governor Scott Walker says he hasn’t ruled out making an endorsement in the Republican primary for U.S. Senate. He says he still has about a week and a half to decide. Walker is immensely popular with Wisconsin’s Republican voters, meaning his endorsement would be very valuable in the tight race. He has remained neutral so far. The governor has complained the four main candidates have spent too much time attacking each other, and too little on talking about their differences with Democrat Tammy Baldwin.