Sen. John McCain’s (Ariz.) clear path to the Republican National Convention travels through critical swing states, but he will likely steer far away from his day job in the United States Senate.

As the battle for the Democratic nomination drags on, Republicans have a significant advantage of rallying around their candidate, who will set the party’s agenda heading into November. Yet McCain faces the daunting task of getting his message out amid all the media attention placed on the race between Democratic Sens. Barack Obama (Ill.) and Hillary Rodham Clinton (N.Y.).

“I don’t think ... it’s a high priority because he is our presidential nominee, and he needs to build his campaign organization out,” Sen. Sam Brownback (R-Kan.), a close adviser to the campaign, said of the possibility of McCain returning to Capitol Hill. “He needs to build the party, and he needs to reach out to all the factions within the Republican Party.”

McCain started to do that Wednesday. He had lunch with President Bush, winning his endorsement at the White House, and then met with officials at the Republican National Committee. Now he’s headed to Florida, one of the most important states in the general election, as Obama and Clinton continue to battle each other on the way to the April 22 primary in Pennsylvania.

McCain’s fundraising numbers have been poor compared with Obama’s and Clinton’s. Until Democrats choose their nominee, a process that may extend beyond the final primary on June 7, McCain’s time would be best spent fundraising and unveiling pieces of his platform in battleground states, people close to his campaign say.  

John Feehery, a Republican strategist and former House GOP leadership aide (and a contributor to The Hill’s Pundits Blog), said McCain should focus on “flushing out” his domestic agenda.

“The least critical thing he should do is make Senate votes,” Feehery said.

Democratic presidential nominee Sen. John Kerry (Mass.) endured criticism from the right in 2004 for missing a slew of Senate votes. However, McCain does not face that risk because his Democratic opponent will also hail from the Senate and miss most votes this year, too. His supporters doubt he will resign his Senate seat, like Kansas Republican Bob Dole did in 1996 when he lost his bid for the White House against Bill Clinton.

“It’s not like John to do that,” said Sen. Joe Lieberman (I-Conn.), the 2000 Democratic vice presidential nominee who plans to campaign for McCain until November. “My guess is that he’ll stay in the Senate and he will be here for the important votes.”

There will be instances when McCain will sense a political advantage to returning to Capitol Hill, according to his allies in Congress, such as in April when the top military commander in Iraq, Gen. David Petraeus, testifies before the Armed Services Committee about the situation on the ground.

McCain, the ranking member on that committee, has staked his political future on the troop surge Petraeus has led and is likely to tout a decrease in violence in Baghdad during the much-publicized hearing.

Other hot-button economic issues, such as trade, may bring him back to the Hill. But his schedule, including a trip to Iraq, may not permit him to participate in next week’s debate over the budget, when a host of politically sensitive amendments over healthcare, earmarks and immigration are expected to emerge. Obama and Clinton are expected to make the trek back to Washington for votes next week, Senate Majority Leader Harry Reid (D-Nev.) said Tuesday.

Even if he’s off Capitol Hill, House Minority Leader John Boehner (R-Ohio) signaled Wednesday that the House, Senate and White House will be ready to “fall in line” behind McCain’s agenda on taxes, spending, healthcare and national security.

Sen. Lindsey Graham (R-S.C.), McCain’s closest ally on the Hill, said the presumptive nominee needs to be “out and about raising money,” building a transition team for the general election and only involved in Senate debates when time permits.

“What you’ll see from John, now until the Democratic nominee is chosen, is, I think, a very focused effort to put together an organization that competes in 50 states to raise the money to be competitive and to start defining the differences,” Graham said.

“John can set an agenda for the party, and Democrats don’t have that luxury right now,” Graham said. “An advantage for them is that you get to showcase the two candidates in a very high-profile way.”

Democrats recognize the difficult situation they are in politically without having decided on a nominee and worry that an increasingly combative race will shadow attempts to portray a positive message for all their candidates. Some fear that disagreements over who should be at the top of the ticket could trickle down to congressional races and hurt the party overall at the polls.

“I think almost every Democrat … thinks winning the general election is of prime importance,” said Sen. Charles Schumer (D-N.Y.), a Clinton supporter and chief election strategist for Senate Democrats. “There will be huge pressure from the party rank and file and the party leadership to make sure that this fight does not become a self-destructive fight.”

Even if McCain stays off Capitol Hill and rolls out his agenda elsewhere, Democrats said Wednesday that they will be able to refocus on him once their nominee is selected.

“The agenda is a third Bush term,” said Sen. Sherrod Brown (D-Ohio), who has not endorsed either Obama or Clinton. “It’s all about continuing the Bush legacy, and the country doesn’t want to continue the Bush legacy.”