WASHINGTON -- If Andrew Jackson created the notion of a president's "Kitchen Cabinet," Sen. John McCain is reinventing it months before his possible election to the White House.
And U.S. Sen. Lindsey Graham seems to be McCain's one-man Kitchen Cabinet.
Graham's visibility as the Arizona senator's closest political confidant has risen in recent weeks as the two men crisscross the country and travel abroad on McCain's presidential quest.
"There's nobody I trust more than Lindsey Graham," McCain, the presumptive Republican nominee, said by phone Thursday from Mexico City. "I'm honored to have him travel with me and give me the counsel I need."
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McCain, 71, praised Graham's "excellent political instincts" and credited the Seneca Republican with helping him win South Carolina's Jan. 19 presidential primary, a crucial victory that made McCain the GOP frontrunner.
The senators' friendship, grounded in Graham's support for McCain's first White House run in 2000, has sparked reports that Graham could be attorney general or fill another senior post in a McCain administration.
McCain, though, said he and Graham haven't discussed any potential Cabinet spots for the Seneca Republican.
"Every indication I have is that Lindsey wants to continue to serve in the United States Senate," McCain said. "He is the author of more legislation than any other senator that I know of who is in his first term."
Graham, who planned to spend Independence Day with John and Cindy McCain at their Phoenix home, said his peripatetic journeys with McCain aren't hindering his duties as a U.S. senator from South Carolina.
"The best thing I can do for my state and my country is to help John McCain become president," Graham said from Mexico. "That is one of the most important responsibilities I will ever undertake. If John wins, the country will go in a completely different direction than Senator (Barack) Obama would take it. I can't tell you how important it is to me."
If McCain defeats the presumptive Democratic nominee in November, Graham said, "we're going to have more conservative judges, we're going to have our taxes lowered, we're going to become more energy independent and we're going to win this (Iraq) war."
Graham all but ruled out accepting a McCain administration post.
"If he gets to be president, I can be of great benefit to him in the Senate," Graham said. "With his agenda, he's going to need people to form bipartisan relationships and pass major legislation. I think that's where I can serve my state best."
Gov. Mark Sanford and U.S. Sen. Jim DeMint, who backed Mitt Romney in the GOP primary season, have been cited as potential running mates of McCain.
In addition to traveling with McCain, Graham has been a frequent advocate in his absence, going to bat for him on the Sunday talk shows and during conference calls with reporters.
Graham, 52, noted that it was he who, after clearing the idea with McCain, first challenged Obama to go to Iraq during an appearance on NBC's "Meet the Press" in late May.
Susan MacManus, a University of South Florida political scientist, said Graham is an effective surrogate for McCain because he is a younger man but an experienced politician.
"He's very adept at talking to the press and can hold his own in tough policy debates," she said of Graham.
Graham isn't the only lawmaker accompanying McCain on his campaign trips.
U.S. Sen. Joe Lieberman, in particular, has also been a frequent traveler.
The Connecticut senator ditched his longtime Democratic affiliation in 2006 after an Iraq war opponent defeated him in their state's party primary. Running as an Independent, Lieberman won re-election in the November 2006 general election.
Though Lieberman still huddles with the Senate Democratic caucus, his efforts to help McCain become president have angered his Democratic peers.
"What Senator Lieberman is doing is heroic," Graham said.
Before going to Mexico, the three men were in Colombia on Wednesday when the government announced the dramatic rescue of 15 hostages who had been held by rebels for years, including three Americans.
Colombian President Alvaro Uribe briefed the three senators on the rescue operation and later called them while they were flying to Mexico to confirm its success, according to Graham.
No one has logged more miles traveling with McCain than Graham.
In the last year, as McCain's second White House campaign all but died and then caught fire, Graham has logged some 42 days on the road with him during trips to more than a dozen states, according to Graham aides.
Going back to the start of the war in 2003, Graham and McCain have traveled to Iraq together seven times.
Graham said he tries to schedule his trips with McCain for when the Senate is in recess for weekends, holidays or other breaks, though he admitted to having missed some votes as a result.
Graham has missed 39 votes in the current session of Congress - which began in January 2007 - for a voting participation rate of 93.5 percent, according to a Washington Post database. DeMint, by contrast, has missed 16 votes for a 97.4 percent participation rate.
Six of Graham's missed votes came last summer while he served in Iraq as a military lawyer as an Air Force Reserves colonel.
As the White House race heats up, Graham increasingly serves as a single-man, rapid-fire response team, rebutting attacks on McCain from Obama or his Democratic allies:
Graham on Tuesday criticized retired Gen. Wesley Clark's claims that McCain's Vietnam War service as a Navy pilot and prisoner of war for five years "isn't a qualification to be president."
Noting that McCain's father and grandfather were four-star admirals, Graham said, "No matter how (Clark) sugarcoats it, he's trying to question John's service."
Two weeks ago, after McCain and Graham both switched positions and backed offshore oil drilling, Graham held a conference call with reporters to stress McCain's pro-environment record.
Graham defended McCain's opposition to a bill to give Iraq and Afghanistan veterans a free college education, saying it would hurt military retention rates during wartime.
"It spends $52 billion to persuade people to leave the military," Graham said.
When the Obama campaign ran a TV ad with veterans criticizing McCain, Graham gave an angry response.
"We're not going to make bad policy because of stupid commercials," Graham said.
But for the most part these days, Graham is in good spirits as he roams the nation and the world with his pal.
Beyond such serious matters as war and energy supply, Graham acknowledged that being part of a presidential campaign is just plain exciting.
"It's a once-in-a-lifetime opportunity for me," he said. "We've got Secret Service protection now. It's like traveling around with a circus."