The Texas senator defended Perry after the governor was indicted Friday.
Santorum is making the three-day trip with Bob Vander Plaats and Foster Friess.
The governor says his decision will come "by the end of this year or the beginning of next."
Presidential aspirants are weighing in on the ongoing tensions in Ferguson, Mo., staking out positions that could reverberate in 2016.
Paul warned of a "systemic problem with today’s law enforcement."
Sen. Ted Cruz on Thursday criticized the arrest of reporters in Ferguson, Mo.
Liberals urge her to stump in Iowa and N.H. even if it stokes White House speculation.
Priebus said Clinton had "failed" to distance herself from Obama's policies.
Sen. Rand Paul (R-Ky.) has work to do if he wants to win the GOP nomination.