It comes down to the following question, for most candidates (other than Cruz):
Who do you trust more - a person that has lied to get elected (Rubio), and may well being lying again (as if Walker would ever build a wall, for example), or a person that may be lying today, based on positions in his past when he wasn’t a candidate or office holder (and many/most of those supposed liberal positions can be debunked)?
Walker has done the things he said he would do and had a hell of a fight with all the leftist establishment arrayed against him and no help from the GOPe.
Despite that Walker beat the leftists over and over.
He has the best track record out there.