By Kathleen Hunter, CQ Staff

Unlike the Republican candidate for president, Arizona’s other senator is generally most comfortable working behind the scenes. But Jon Kyl has put himself close to the spotlight at both of this summer’s political conventions while working overtime to drum up enthusiasm for his home state colleague, John McCain .

Last week, he flew to Denver to join the corps of Republican officials defending their presidential candidate against the verbal barbs hurled at the Democratic National Convention. And on Wednesday night, he took as much of a national star turn as he’s ever done before by giving the nominating speeches for McCain at the Republican National Convention.

“John has never been afraid to make tough calls,” he told the delegates at the Xcel Energy Center in St. Paul a few minutes after Gov. Sarah Palin of Alaska’s speech. ”He’s the right man at the right time to lead us as president.”

Unlike the presidential candidate, who’s reputation is for glibly answering pretty much any question a reporter lobs at him, Kyl’s reputation is that of a policy wonk who often shies away from reporters and prefers digging into complex legislative issues to headlining press conferences.

It’s those qualities that have earned Kyl a reputation as one of the Senate Republicans’ most conscientious workhorses and propelled him at the end of last year into the No.2 job in his caucus, minority whip.

“Kyl is more of a laid-back worker,” said Randy Pullen, chairman of the Arizona Republican Party. “He’s not nearly out in the press as much as Sen. McCain is, but that’s the way he prefers to work. He just gets things done.”

But ever since McCain emerged this winter as the party’s presumptive nominee, Kyl, whose resume is filled much more with partisan spadework than the maverick McCain’s, has worked as an emissary from the campaign to the party’s conservative base.

Observers note that Kyl has met with conservatives — both formally and informally — to help reassure the base about McCain, who, in his 25-year legislative career, has strayed from the GOP mainstream on issues ranging from campaign finance to global warming to immigration.

“It would not surprise me at all if Jon Kyl was doing all kinds of things to help John McCain gain credibility and get his message out in those audiences,” said Rep. John Shadegg , a staunch conservative Republican conservative from Phoenix.

But it was Kyl’s foray into Democratic territory that sealed his status as a top-tier surrogate. Among the others in Denver last week were vice-presidential contenders such as Gov. Tim Pawlenty of Minnesota and former Gov. Mitt Romney of Massachusettss and other 2008 presidential aspirants including former Mayor Rudolph Giuliani of New York.

“You couldn’t pay Jon Kyl to go to Denver for a Democratic convention,” Shadegg said. “But for John McCain he did . . . He won’t volunteer to jump into a fight that’s not his, but he’s a good foot soldier.”

The work on McCain’s behalf continued in earnest this week in the Twin Cities, where Kyl arrived on Monday — after a trip home to Arizona for the weekend — for another whirlwind round of surrogate events. (Kyl just began his third, six-year term, having won in 2006 with 53 percent of the vote in Arizona, and so has more time to devote to others’ campaign this fall than many lawmakers.)

On Tuesday, he gave a breakfast speech to Maryland delegates and conducted several interviews along “radio row,” the complex set up for talk show hosts just down the hall from the convention hall in St. Paul, before heading to Minneapolis to participate in a panel discussion on how McCain would govern in the White House.