SEDONA, ARIZ. - Within minutes of the confirmation on Saturday morning that Sen. Joseph Biden would be on the Democratic ticket, aides to Sen. John McCain shot out a statement and released an advertisement that pointed out that Biden, a Delaware Democrat and an also-ran in the 2008 primaries, had described Sen. Barack Obama as not ready to be president.

"John McCain is a personal friend, a great friend, and I would be honored to run with or against John McCain, because I think the country would be better off," Biden, speaking seriously, told the comedy host Jon Stewart in 2005, in a video clip that instantly found its way into a new McCain TV advertisement.

McCain and Biden are longtime political rivals but personal friends. Those ties made it less than surprising that McCain picked up the phone Saturday morning to call his old pal.

"It was a brief call between friends," said McCain spokesman Tucker Bounds. "John McCain simply called to congratulate him and let his friend know he was thinking about him and his wife."

That's how things work in the Senate, where shifting alliances are the order of the day and today's ally can be tomorrow's rival.

There's considerable history between the two, and a lot of shared years in Washington. They've forged alliances over the years, and compliments have often flowed between them.

Maverick status

Biden suggested in the 2004 election cycle that McCain could build ties with Democrats. McCain's maverick status may have alienated some Republicans, but it made him appealing to Democrats, Biden noted.

"I think that this is a time for unity in this country and maybe it is time to have a guy like John McCain -- a Republican -- on the ticket with a guy he does like," Biden said, referring to 2004 Democratic presidential nominee John Kerry.

McCain spent his weekend mulling his own vice presidential pick, recording material for more TV commercials in the spectacular rock formations of the surrounding landscape and practicing his acceptance speech for the Republican National Convention.

Mark Salter, the senior aide who was one of the principal authors of the address, said on Friday, "I know he's working on the speech, because they're phoning in edits every few hours."

While the political spotlight was on Obama and Biden in Springfield, Ill., McCain reduced his public appearances to coffee runs to Starbucks. He also spent time in interviews. CBS' "60 Minutes" was in Sedona on Friday, and Katie Couric was expected to interview McCain over the weekend.

Two top McCain aides, Charlie Black and Nicolle Wallace, are with the candidate, who has been off the campaign trail for three days, but there was no word from them on whether he has settled on a running mate.

Sources close to the campaign said that Mitt Romney, former governor of Massachusetts, remained a top possibility.

The New York Times and Associated press contributed to this report.