Several college student leaders volunteering with the Paul campaign said his bid to end the war on drugs is what initially attracted many of their peers. But it is his strict constitutionalist views and air of authenticity that keep students coming back. Paul’s appearances at colleges routinely draw standing-room only crowds.

“A lot of people my age are rejecting the notion that the US has a right to go anywhere it wants to in the world,’’ said Ryan Lockard, a 21-year-old biology major at the University of Northern Iowa who leads the campus chapter of Youth for Ron Paul. “The Iraq war debacle is a big part of it.’’

Young people, traditionally the least likely demographic to vote, let alone caucus, have mobilized around the 76-year-old congressman’s campaign unlike any other candidacy, with Youth for Ron Paul chapters springing up at many college campuses here in recent months. Hundreds of college-aged volunteers around the nation plan to give up a week of their holiday break and descend upon Iowa after Christmas to knock on doors, make phone calls, and motivate voters to turn out for the caucuses.

Paul’s anti-establishment policies resonate with a deep well of grassroots supporters who include a vocal segment of the Christian right here in Iowa who do not believe in nation building at the point of a sword - even when it comes to protecting Israel - as well as college students who have lived much of their lives knowing only a nation at war.

Paul has also laid some of the blame for the Sept. 11 terrorist attacks on US foreign policy and advocated normalized relations with Cuba.

During last week’s debate in Sioux City, the Air Force veteran criticized what he considers undue concern in Washington over the possibility of Iran developing a nuclear weapon. “It’s another Iraq coming,’’ he said. “There’s war propaganda going on. . . . The greatest danger is that we will have a president that will overreact and we will soon bomb Iran.’’

Many conservatives characterize Paul’s foreign policy stance as extremist, isolationist, and anti-Israel, calling it a weakness that caps his support. Nearly half of those polled by ABC News and the Washington Post said it is a major reason to reject him. But with less than two weeks to go before Iowa’s first-in-the-nation caucuses, those views have not stopped - and may have helped - Paul in his emergence as a real threat to front-runners Newt Gingrich and Mitt Romney.

DOWS, Iowa - He has set himself apart from the rest of the Republican field as the candidate who believes the United States should shed its role as the world’s policeman and focus instead on its internal economic problems. Representative Ron Paul of Texas says he would cut a trillion dollars out of the federal budget his first year as president, in part by ending all foreign wars and foreign aid, including to Israel.

“Young conservatives want to see somebody who wants to tackle the spending issue and stop kicking the can down the road and putting the burden on us,’’ said Ben Levine, a Drake University sophomore and precinct captain for Paul. “It’s not that we’re a bunch of hard-core antiwar protesters, but I think we need to be a little more humble and prudent with how we deal with our foreign policy.’’

College-aged voters also appreciate that Paul would not put men and women of their generation in harm’s way unnecessarily.

“We just went through that with Iraq, and we can’t afford it,’’ Levine said.

Many Christian conservatives, though, see Paul’s policy toward Israel as his greatest liability, in addition to his libertarian views on social issues that keep him from supporting constitutional amendments against same-sex marriage and abortion.

“Most evangelical Christians believe we have a duty to protect the nation of Israel,’’ said Steve Scheffler, president of the Iowa Faith and Freedom Coalition.

On Thursday, Gingrich joined in the criticism of Paul for minimizing threats to the United States and Israel in an interview with a conservative radio commentator.

The Rev. Albert Calaway, a retired Assemblies of God minister and influential Iowa pastor who recently endorsed former senator Rick Santorum of Pennsylvania, told the Des Moines Register that Paul is “unacceptable to many evangelical Christians in Iowa because he would cut off all US military aid to Israel, possibly creating conditions for a Holocaust in the Holy Land.’’

“Imagine singing ‘O Little Town of Bethlehem’ after a President Ron Paul turns his back on God’s chosen people and Islamist missiles or ovens fill Israel’s skies with blackness,’’ Calaway said.

Paul, who was the only serious candidate not invited to a recent Republican Jewish Coalition presidential forum in Washington because of his views, has said repeatedly that his support for Israel means treating it “as an independent nation and not as a puppet of our state.’’

Drew Ivers, Paul’s Iowa state chairman, admits it has been a challenge for the campaign to break through to the wider Christian community with Paul’s message of simply wanting to give Israel “the autonomy to self-govern, self-defend, and self-determine their own destiny.’’

But he said the campaign is securing more endorsements each day from Christian pastors as Paul’s explanation is better understood.

Paul can also rely on a tightly organized troop of loyal, motivated volunteers, many of whom have honed their message since his failed presidential bid in 2008.

After Sunday services at a church basement in Dows, a rural town about 90 minutes from Des Moines, half a dozen Christian families who home school their children gathered for a potluck and political discussion with their pastor, Doug Holmes, an ardent Paul supporter who also caucused for him in 2008.

“The church is misguided in thinking that we somehow have a right to interfere in another nation’s business,’’ said Holmes, a Vietnam veteran. “The mission for the church is to take the gospel to the world and effect change, but it says nothing about nation building at the point of a sword.’’

Ed Sents, a 27-year-old farmer and father of three, also plans to support Paul on Jan. 3. “Some Christians think we need to take the fight to the Muslims before they take it here, but pre-emptive strike is not just war,’’ he said in reference to Iran’s potential of building a nuclear weapon.

Rick Grote, a new parishioner and pharmacist who serves as a county and precinct coordinator for Paul, recalled a November candidates forum at a Des Moines church during which the 2,500-person crowd of social and religious conservatives leapt to their feet and applauded wildly after Gingrich said the United States should protect Israel against Iran no matter what the rest of the world thinks.

“Evangelical Christians in Iowa are antiabortion, but they have this thing about war,’’ Grote said. “Don’t Muslim kids have a right to live? They think we have to bomb the snot out of them before they come over here and bomb the snot out of us.’’

Tracy Jan can be reached at tjan@globe.com.

© Copyright 2011 Globe Newspaper Company.