"Ted Cruz is spellbinding, a tremendous orator and principled," Santorum said on Glenn Beck's radio show, CNN reports.
"He understands these issues at his core. We need people who can motivate and lead. Ted has that capability."
Cruz, a former state solicitor general, stands as the leading opponent of Lt. Gov. David Dewhurst in the race to replace retiring Republican Sen. Kay Bailey Hutchison.
A Public Policy Polling survey from earlier this week shows Dewhurst with a commanding lead of 46 to 29 percent over Cruz. Former Dallas Mayor Tom Leppert placed third with 15 percent support, and ESPN sportscaster Craig James fourth with 3 percent. A candidate will need more than 50 percent of the vote to avoid a runoff.
Cruz has drawn the support of in-state tea partyers in addition to national conservative groups, such as FreedomWorks and Club for Growth. In addition to Santorum, former Alaska Gov. Sarah Palin has thrown her support to Cruz. She even recorded a robo call for him, which produced a "huge surge" for the candidate, his campaign said.
Presidential candidate Ron Paul also is backing Cruz.
Dewhurst hasn’t lacked for support from national GOP heavyweights either. He released ads in recent days that included Texas Gov. Rick Perry and former Arkansas Gov. Mike Huckabee.
"Plenty of candidates say they're conservative," Huckabee says in the latest TV ad. "But the only proven conservative in this Senate race is David Dewhurst."
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