Former presidential candidate Tommy Thompson endorses Rudy Giuliani:

"I want a candidate that's going to be able to stand up and be able to win the Republican primary and take on Hillary Clinton and win," added Thompson, the first former 2008 Republican candidate to make an endorsement.

Thompson, a former Wisconsin governor, served as secretary of Health and Human Services during President Bush's first term. In his presidential race, he struggled to raise money and gain support.