(AP) _

An Omaha banker is kicking off his U.S. Senate campaign with a vow to serve no more than two terms if elected.

Pinnacle Bank chairman Sid Dinsdale pledged to serve as a "citizen senator'' during a campaign stop in Lincoln. The Republican hopeful cast himself as a pro-business conservative with experience in agriculture.

Dinsdale also received an endorsement from former Nebraska athletics director Tom Osborne, a longtime friend and former congressman.

Dinsdale is the fourth GOP candidate to jump into the primary. The candidates are looking to replace Republican U.S. Sen. Mike Johanns, who is not seeking re-election. So far, no Democrat has entered the race.

The other candidates are Omaha attorney Bart McLeay, former State Treasurer Shane Osborn, and Ben Sasse, the president of Midland University in Fremont.