Having fallen from frontrunner status in the race for the GOP presidential nomination, Sen. John McCain (Ariz.) has done more than simply reshuffle his campaign — he’s seemingly decided to put a new premium on being a U.S. Senator.

Once a steady no-show on Capitol Hill, McCain has been seen uncharacteristically often over the past couple of months in the halls of the Senate, casting votes, participating in press conferences and managing defense legislation on the floor. And while he still ranks second in the Senate for the most votes missed this year with nearly 50 percent (according to a washingtonpost.com database), McCain’s made 55 percent of the Senate’s tallies since July and has been present for most of the high-profile debates.

In large part, McCain’s increased role in the Senate can be linked directly to the issues now before the chamber. But beyond that, his allies say, McCain is re-engaging because he recognizes it is one of the best venues to showcase his decades of experience and knowledge on foreign and domestic policies.

“The issues we’re on are important to John and they happen to be important to the country,” Sen. Richard Burr (R-N.C.) said. “What you are seeing firsthand is a different John McCain than you saw a few months ago — he’s focused and energized.

“One might conclude that John McCain runs better from behind.”

“Overall, he’s retooled his organization, and he’s got his mojo back,” agreed Minority Whip Trent Lott (R-Miss.), one of McCain’s most vocal Senate backers. “It’s going to help him. You are going to see him inch back.”

McCain’s recent Congressional exposure is indeed tied to his status as the ranking member on the Armed Services Committee, which has given him the podium to lead his party during the Senate’s current debate on the Defense authorization bill. Consideration of that measure also has allowed McCain to command center stage and reiterate his case for supporting the ongoing troop “surge” in Iraq.

In a brief interview last week, McCain said his recent attention on his Congressional duties stems partly from his position on the Armed Services panel, but also from “the gravity of the issue.” McCain noted that he suspended 10 days worth of campaign activity so he could focus fully on the troop withdrawal debate in the Senate.

Asked whether he planned to continue a trend of spending more time in the chamber, McCain said: “It depends on which bill. Sure, there will be issues that require me to be here. It goes with the job.”

But that hasn’t always seemed to be the top consideration for McCain, especially during the first part of the year when he rarely was seen outside of the early presidential primary states of New Hampshire, Iowa and South Carolina. While other Senate presidential hopefuls seemed intent on keeping a decent record for casting votes — including several earlier in the year on the Iraq War — McCain remained largely out of sight.

So far this year, presidential candidates and Democratic Sens. Barack Obama (Ill.), Chris Dodd (Conn.) and Joseph Biden (Del.) have each skipped close to 25 percent of the votes cast, while Sen. Hillary Rodham Clinton (N.Y) has missed just over 8 percent, according to the Post’s data. On the GOP side, candidate and Sen. Sam Brownback (Kan.) has missed fewer votes than McCain, but more than the Democrats, with 36 percent.

Those missed votes haven’t gone unnoticed for any of the candidates, but especially for McCain, who prior to the 110th Congress had an infamous reputation for his prolific involvement in issues and comfort with the media.

One of his biggest ribbings came last spring, when McCain made a rare appearance in the Senate to join his colleagues in announcing a long-awaited deal on immigration reform. While in the past a key negotiator on the issue, McCain had opted to hand off his at-the-table position this year to his friend Sen. Lindsey Graham (R-S.C.) and as such was not involved intimately in the talks.

McCain’s decision to fly in to take part in the deal’s announcement brought with it both media and Senate attention and led to a well-publicized spat with Sen. John Cornyn (R-Texas), during which Cornyn — who opposed the deal — accused McCain of “parachuting in on the last day” and trying to weigh in. The quarrel culminated in McCain issuing an obscene directive at Cornyn.

Since then, however, sources say McCain has appeared to regain an appreciation for his long Senate résumé. They add that McCain has a better understanding that the issues facing the Senate reflect directly on the strengths of his candidacy.

“He was the frontrunner — a position he’s not accustomed to,” Graham explained. “He had to start calculating how to be a frontrunner and he’s not really good at that. He’s good at focusing on the issues he’s passionate about and campaigning at the grass roots.”

“It’s a smart move,” said a Republican source familiar with McCain’s campaign. “It shows him as an impact player.”

McCain’s Senate evolution isn’t necessarily a surprise following his near career-ending stretch on the presidential campaign front. In fact, McCain still lags in fundraising behind his top rivals, continues to wade through a major internal reorganization of campaign staff and continues to be dogged by his unwavering support of an unpopular war.

Those circumstances have pushed McCain — once viewed as the Republicans’ leading contender in 2008 — down to the middle rung of candidates. Many pundits have since discounted him as a viable hopeful against the money and popularity of ex-New York Mayor Rudy Giuliani, former Sen. Fred Thompson (Tenn.) and former Massachusetts Gov. Mitt Romney.

While not considered in that top tier, Brownback said he too shares the challenges of a Senator trying to compete against a field of presidential candidates, many of whom aren’t balancing the duties of an elected office. Brownback called it “very difficult.”

“I’m now trying to be more selective,” Brownback said. “I try to make as many votes as I possibly can, and as many key events. There’s a lot of pressure to be out there.”

Whether McCain can effectively reinvent himself on the trail remains to be seen, but what also is unclear is whether his attendance record will continue to improve in the Senate. The next big test, his allies and detractors both say, will come this fall as the Senate takes up the outstanding appropriations measures, a debate that would give McCain the chance to weigh in on the popular conservative issue of fiscal restraint — a cornerstone of his campaign.

“The fact is, what’s most important and what’s going on right here are some of the strongest suits of John McCain,” Burr said.