WASHINGTON — When Pope Benedict XVI visited the nation's capital last month, Sen. Sam Brownback did a little preaching to Catholics himself — the gospel according to John McCain.
Once McCain's rival for the White House, the Kansas Republican is helping to spearhead McCain's effort to woo Catholic voters.
With Democrats flush with advantages, McCain hopes that Brownback's street cred among religious conservatives could help tip a swing state or two his way.
"He has a big following in the conservative wing of the party with right-to-life supporters and those who care about social and cultural issues," said Charlie Black, a McCain senior adviser and a veteran of Republican presidential politics, "and he has been terrific at promoting McCain among those groups."
Brownback endorsed McCain last fall after dropping out of the presidential race. Now his political network drives the presumptive Republican nominee's Catholic outreach.
It helped McCain's ground game during the Florida primary in January, when his victory over Mitt Romney sealed him as the front-runner.
But McCain also has stumbled. His long pursuit of pastor John Hagee's endorsement backfired when the evangelical preacher's anti-Catholic statements — he referred to the church as "the great whore" — rippled through the media.
Hagee, who runs a 19,000-member mega-church in Texas, has apologized. But McCain had originally said that he was "very honored" to have Hagee's support.
The episode showed that either his campaign's vetting of Hagee was careless or that it knew about the controversial remarks but decided the political benefits outweighed any embarrassment or Catholic backlash.
The pope's visit to Washington was a chance to showcase McCain before high-profile Catholics. A Catholic himself, Brownback hosted the pontiff at the National Catholic Prayer Breakfast, where he was warmly greeted by 1,000 prominent faithful.
Brownback also entertained some of McCain's leading Catholic supporters at a more intimate gathering that week at the Metropolitan Club, one of the capital's storied havens for political business and quiet talk.
The presence of Cindy McCain, the candidate's wife, and Rick Davis, his campaign manager, said all anyone needed to know about the importance they placed on Catholic support.
Catholics "will be swing voters," Brownback said. "They are key votes."
And they no longer are a rock-solid part of the Democratic base. President Bush proved that in 2004 when he won 52 percent of the Catholic vote, even though Democratic Sen. John Kerry was the first Catholic major party presidential nominee since John Kennedy in 1960.
But William Donohue, president of the Catholic League for Religious and Civil Rights — and who pounded McCain over the Hagee endorsement — said that while "everybody knows Jews will go with Democrats and Protestants will go with Republicans," Catholics were "politically homeless."
"They are there for the taking," he said. "Bill Clinton did an excellent job reaching out to Catholics. Hillary (Clinton) has done a good job. (Barack) Obama has real problems. Whoever wins the Catholic vote stands to win the White House. That's why it is critical."
McCain backers are encouraged that several states with large blocs of Catholic voters could be fertile ground this fall. In 2004, Catholics accounted for more than 25 percent of the turnout in Ohio, Minnesota, Michigan, Wisconsin, Pennsylvania and New Jersey.
"States with high concentrations of Catholics tend to be some of the more important swing states," Black said.
Brownback, 51, co-chairs the National Catholics for McCain Committee with former Oklahoma Gov. Frank Keating. An evangelical Christian before converting to Catholicism in 2002, his politics have always been steeped in faith.
Brownback has been the go-to lawmaker for social conservatives on divisive political hot buttons such as abortion and gay marriage.
But he's worked across the aisle with Democratic liberals such as Clinton and the late Sen. Paul Wellstone on social justice causes such as sexual trafficking and famine.
Tasking him with religious outreach is like asking Tiger Woods to play a round at Augusta National, where he's won four Masters tournaments.
Brownback knows the contours of the terrain: where it's hazardous, where to be aggressive and where to lay back.
"What's important is that Senator Brownback will have the ear of John McCain," said Steven Wagner, who ran Catholic outreach for the Republican Party in 2000. "He will be able to advise Senator McCain on what Catholics are concerned about, what they want to hear from their presidential candidates. It's the presence of the Catholic mentality to the campaign. That is his role."