WEST DES MOINES, Iowa — In Iowa, the evangelical vote can make or break a campaign — which is why both Texas Sen. Ted Cruz and Donald Trump are battling over support from the most conservative voters, as the race heats up ahead of the state’s leadoff caucus.

Cruz courted hundreds of social conservatives and evangelical voters who packed a Wednesday night rally, where he touted his anti-abortion beliefs while drawing sharp contrasts with Trump and his record on a variety of issues, including changing his position on abortion. Cruz also suggested that Trump doesn’t have the humility or temperament to be president.

Winning evangelical voters — who catapulted underdog candidates to victory in Iowa in 2008 and 2012 — is essential for Cruz to do well when Iowans vote on Monday.

“If evangelical pastors move the pews to the caucuses, then Ted Cruz wins Iowa,” said David Lane, an influential activist who has organized events across Iowa where Cruz and other Republican candidates have addressed pastors.

On Monday, Cruz addressed about 250 pastors in Cedar Rapids and Des Moines. He gave his own assessment of where he sees the race, should Trump prevail in Iowa.

“If Donald wins Iowa, he right now has a substantial lead in New Hampshire,” Cruz told Iowa pastors at the closed-door meeting, a comment first reported by the Christian Broadcasting Network and confirmed by Lane. “If he went on to win New Hampshire as well, there is a very good chance he could be unstoppable and be our nominee.”

A day later, Cruz offered a different view while speaking to reporters, downplaying the need to secure a win in Iowa.

“We are running a national campaign,” Cruz said in Albia, Iowa. “From the beginning we’ve said no state is a must win for us.”

Lane said Cruz needs to win Iowa to stop Trump, and to do that, his evangelical supporters must turn out come caucus day.