Posted Saturday, May 12, 2012 --- 9:20 a.m.

GREEN BAY, Wis. (AP) — Four Republican candidates in the race to fill an open U.S. Senate seat are vying for the official endorsement of the state party.

Each candidate will address Republican delegates who are gathered Saturday in Green Bay for the state party convention. Sixty percent of delegates must vote to endorse a candidate or there will be no endorsement.

The candidates are former Gov. Tommy Thompson, hedge fund manager Eric Hovde, state Assembly Speaker Jeff Fitzgerald and former U.S. Rep. Mark Neumann.

All four have been working behind the scenes to gather the necessary support to get the endorsement, which provides them with the party's network of contacts, money and official support for the primary.

U.S. Rep. Tammy Baldwin is running as a Democrat.

Copyright 2012 The Associated Press.