The administration of President-elect Barack Obama likely could reach out to McCain, who battled Barack for the White House, on issues for which a consensus is needed, CNN reported Wednesday.
"You could have a McCain as a centrist who plays the role of consensus-builder on a lot of issues," Senate historian Donald Ritchie said.
McCain could position himself as an ally of the Obama administration while advocating causes he has always championed, such as earmark reform, climate change and immigration reform, observers said.
"John McCain's days as a presidential candidate are over, and his chance now to leave a lasting impression in public life going forward probably involves working with the man who beat him for the presidency: Barack Obama," Time magazine's Mark Halperin told CNN.
McCain's return to the upper chamber Tuesday was low-key as news about two other senators dominated headlines, Politico reported. Convicted felon Sen. Ted Stevens, R-Alaska, lost his bid to return to the Senate and the Democratic caucus voted to let McCain's friend Sen. Joe Lieberman, Ind-Conn., keep his Homeland Security committee chairmanship.
"There's a swirl of activity going on today," Sen. John Thune, R-S.D., told the Washington publication. "And it's easy to be eclipsed by all of that."
But Republican senators, seeing their number dwindle, are glad McCain's back, Thune said
"We need him. We need the John McCain we all know and appreciate," he said to Politico. "We need him standing tall."