John McCain won't be standing before the American people on January 20 to be sworn in as the next president. Instead, the longtime Arizona senator will be returning to Congress, where it's expected he'll continue to reach across the Senate aisle and remain a powerful voice for the Republican Party.

"John is someone who has always served his country and he has his entire adult life, and I anticipate that after some time off, well deserved, and some time with his family, well deserved, he'll be back in Washington, rolling up his sleeves and getting back to work," John Weaver, McCain's former top campaign strategist, told FOXNews.com.

"This is his last run, obviously, for national political office, but he's still got many years of service ahead of him," Weaver said.

Weaver said he thinks McCain will be a positive voice for Republicans who will find themselves in the minority in both the House and Senate when Congress convenes in January.

"John McCain will be John McCain. I think he'll continue to be a maverick in the Senate. He'll continue to be a voice of leadership and a voice of opposition to the coming administration. And his voice will carry a great deal of weight for both the party and the country," said Michael Steele, former lieutenant governor of Maryland and chairman of GOPAC, a conservative political organization.

McCain has two more years remaining in his fourth term in the Senate, and there's no reason to suspect he won't run again -- and win -- in 2010.

"He's won all of his elections by pretty good margins, even when he had some reasonable competition," said University of Arizona political science professor Barbara Norrander. "He's been able to win his elections handily, and most of the polls show him to be pretty popular -- and not just with Republicans. With Independents and even some Democrats as well."

McCain's office confirmed that he'll be back in Washington to finish out his term, but didn't have any other information on the senator's plans.

He will be 74 years old on Election Day, 2010.

The Republican candidate conceded defeat and congratulated President-elect Barack Obama on Tuesday night after a grueling and expensive battle for the presidency.

In exit polls, many Americans said McCain's age was a bigger factor than Obama's race when it came to choosing the next president.

"This is an historic election, and I recognize the special significance it has for African-Americans and for the special pride that must be theirs tonight," McCain told supporters.

"Its natural tonight to feel some disappointment, but tomorrow we must move beyond it and work together to get our country moving again," he said.