Clinton, Iowa (CNN)The final days before the first-in-the-nation caucuses are agonizing for many Iowa evangelicals as they waver between Ted Cruz and Donald Trump.

At events for both GOP presidential candidates across the Hawkeye state, voters say they are torn between backing the committed Christian conservative who is solid on their principles, or the once-liberal, thrice-married candidate who they believe would make the stronger president.

While many had assumed that Cruz would have a lock on white evangelical voters, particularly as support for retired pediatric neurosurgeon Ben Carson has waned, Trump has shown surprising strength within that voter group. In a Wall Street Journal/NBC News/Marist poll released Thursday, Trump notched the support of 31% of evangelical Christians to Cruz's 28%. But in a poll of likely Iowa caucus participants released earlier by Quinnipiac University, Cruz led Trump among white born-again evangelicals 34% to 27%.

Florida Sen. Marco Rubio's efforts to reach evangelicals also appear to be paying dividends after a month in which he has emphasized his faith. Though Rubio is far behind Trump and Cruz in Iowa polls, a number of evangelicals mentioned him as their third choice in interviews over the past week and he is rising in the polls.