FAST FIVE: 'William Who?' – Former Massachusetts Gov. To Challenge Trump For Republican Nomination
Larry Hogan, another credible challenger from what's left of the party's moderate wing, has ruled out a run.
Abortion: Weld supports abortion rights and has fought to protect them.
As governor in 1991, he introduced a bill aiming to make it easier to get an abortion in Massachusetts.
He also signed a 2013 amicus brief in support of same-sex marriage.
Economy: Despite his more progressive social views, Weld is a traditional conservative when it comes to the economy, prioritizing cutting spending and cutting taxes.