Ted Cruz predicted Thursday morning that he could win the Republican race for the White House within the next three months, telling supporters to prepare for a "90-day sprint" to clinch the nomination.

"There is a very good possibility that the Republican primary will be decided by the end of March," the Texas senator told volunteers on a conference call in which he also rallied them against an anticipated deluge of attack ads.

"Strap on the full armor of God" for the negative advertising that is coming, Cruz told volunteers, predicting that foes could spend tens of millions of dollars against him in January alone. "We ain't seen nothin' yet."

Cruz urged supporters to remain upbeat as he faces a heightened level of scrutiny from his detractors, who are increasingly setting their sights on the Texas senator in Iowa. His opponents, he warned, will "toss out any lie, toss out any attack, and the attack will do its damage before anyone discovers it’s not true."

The call came a day after Cruz's campaign announced it had raised $20 million in the fourth quarter of 2015, its biggest haul yet. Cruz assured supporters he would be a responsible steward of their dollars, using as an example the fact that his consultants do not earn a share of media buys.

“If that’s how you’re getting paid, suddenly spending $10 million on TV commercials sounds like a good idea," he said.

The call contained little talk of Cruz's GOP opponents, save for a few references to his closest competition in many early voting states: billionaire Donald Trump. Mark Campbell, Cruz's political director, told volunteers that a growing chunk of the "establishment wing of the Republican Party is coming to our campaign as the alternative to Mr. Trump."

Cruz returns to the campaign trail Monday, when he is set to begin a six-day, 36-county bus tour of Iowa.