WASHINGTON – Two years after Mike Pence helped convince evangelical Christians to back Donald Trump's presidential bid, the vice president warned faith voters that complacency is the greatest threat to Republicans keeping control of Congress.

"The other side is mobilized, and some say they’re motivated as never before," Pence said Saturday at the Family Research Council's Voter Values Summit. "But I say we must match – in fact, I say we must surpass – the energy of the American left and their enthusiasm and passion."

He called the midterm elections a "choice between a party that celebrates America and one that often demeans millions of our neighbors and friends."

"Let’s keep faith that He who has ever watched over this nation still governs in the affairs of men," Pence said.

Pence vouched for Trump's anti-abortion credentials and his support for other issues important to conservative Christians before the 2016 election, one reason Trump received more of the white evangelical vote than the past three GOP presidential candidates.

Since Trump took office, many Christian conservatives said they have been more than rewarded for their faith in Trump and want to make sure his policies continue.

"He has systematically followed through on his promises, whether it is rebuilding our nation's military, whether it is restoring religious freedom in the country," said Tony Perkins, president of the Family Research Council.

They know they have to match the enthusiasm on the other side.

“I am worried about intensity among liberal and Democratic voters,” said Ralph Reed, head of the Faith and Freedom Coalition, which has launched its most ambitious voter outreach campaign ever. “The other side is coming, and they’re coming in record numbers.”

About half of voters said this summer that they are more enthusiastic about voting this year compared with previous congressional elections. That’s the highest level recorded by the Pew Research Center for midterm elections since it started asking the question in 2006.

Forty-seven percent of white evangelical Protestants were more enthused, compared with 51 percent of all registered voters.

White evangelical voters were less likely to have attended a political rally or event or to have worked on a campaign. They were more likely to have expressed a political opinion on social media.

"They’re unified," Values Voter Summit attendee Elizabeth Harrison said of Democrats. "Republicans are not."

Harrison, 68, a nurse from Virginia, said she voted for Trump mostly because she did not think Hillary Clinton would stand up for people of faith. She approves of the job Trump has done and worries that "all the gains will be gone" if Democrats win control of Congress.

"I think Donald Trump’s presidency is at stake," she said.

In the last election, 81 percent of white evangelicals voted for Trump. That’s a greater share than supported George W. Bush in 2004, John McCain in 2008 or Mitt Romney in 2012.

During a White House dinner for evangelical leaders in August, Trump touted the steps the administration has taken to curtail abortion, elevate religious protections and recognize the capital of Israel.

“Every day, we’re standing for religious believers,” Trump said during the portion of the dinner that was open to the news media.

After the cameras left, Trump questioned whether his conservative base would turn out in November since he won’t be on the ballot, according to an audiotape of his remarks provided to The New York Times.

Trump warned that Democrats “will overturn everything that we’ve done, and they’ll do it quickly and violently” if Republicans lose control of Congress.

Conservative faith leaders have been “absolutely brilliant” at stoking a sense of urgency and a fear that civilization will collapse if voters don’t get to the polls, said Marie Griffith, director of the Danforth Center on Religion and Politics at Washington University.

“When people think, `Oh, that’s not going to happen this time,' it does,” she said.

The controversial confirmation battle over Supreme Court nominee Brett Kavanaugh amplifies the battle cry this year, just as judicial nominations, in general, were a top motivating factor for conservative voters in 2016.

When Senate Majority Leader Mitch McConnell, R-Ky., addressed the Voter Values Summit on Friday, he promised that Kavanaugh would be confirmed. He urged the activists not to get rattled.

“If we can hold on to the Senate majority for two more years, we’re going to transform the federal judiciary with men and women who believe in this vision of America,” McConnell said.

The Faith and Freedom Coalition’s voter mobilization efforts are focused on 10 states where there are top Senate races and nine with significant gubernatorial or House races.

Working off a database of 27 million evangelical and anti-abortion Catholic voters in those states, staff and volunteers will contact each voter an average of seven to 12 times, Reed said. Communication will include voter guides distributed in churches, phone calls, texts, digital ads and showing up at more than 2 million homes.

By comparison, the group knocked on 1.25 million doors for the last presidential election.

The message this year is that if Democrats take control of Congress, they will try to take Trump down, and they will stop approving his nominations.

“That’s what’s at stake: impeachment and judges,” Reed said.

The Family Research Council is launching a bus tour of 12 states, building up to a 90-minute national simulcast event the Sunday before the election to talk about issues and to pray.

"I do believe this fall's election is challenging," Perkins said. "But I do believe the values voters who are more in tune, and more astute, than they're given credit for in the media know what's at stake."

There are evangelical Christians opposed to Trump’s policies, but they’re not organized on the same scale.

“This November, we have a real opportunity to pivot to a more authentic path of faith,” says the website of Vote Common Good, a group led by a Minnesota pastor that has more than two dozen upcoming events for House races across the country.

Some prominent faith leaders have spoken out against Trump, such as Peter Wehner, a senior fellow at the Ethics and Public Policy Center who served in the Reagan and George H.W. Bush administrations. Last year, after Trump supported Roy Moore, the Alabama Senate candidate accused of sexually assaulting teenage girls, Wehner wrote an opinion piece titled “Why I can no longer call myself an evangelical Republican.”

Griffith of the Danforth Center on Religion and Politics doubts such public stances have much impact on the average evangelical voter.

“Those folks look like elites (to those) on the ground,” she said.

To Gary Burkle, a mental health counselor from Columbus, Ohio, attending the Values Voter Summit, the event looked like the precursor to another electoral victory.

"Our people will do," he said, "what they did in 2016."