(AP) - John McCain said Thursday he had yet to decide on a running mate.
The Republican presidential nominee-in-waiting was expected to name his vice presidential pick later this week.
The hope is to curb any uptick in polling that Democratic nominee Barack Obama could get from his convention wrapping up Thursday in Denver and to create momentum heading into the Republican convention next week in St. Paul, Minn.
McCain and his running mate then are expected to appear together at one or more rallies, including one planned for Saturday in Pennsylvania.
McCain said in an early morning radio interview that he was bringing both former Pennsylvania Gov. Tom Ridge and former Massachusetts Gov. Mitt Romney, two of the leading names on his short list. But he cautioned against assuming that meant either one would be the pick.
Inside GOP circles Thursday, speculation swirled around Democrat-turned-independent Sen. Joe Lieberman of Connecticut.
"I haven't decided yet, so I can't tell you," he told KDKA NewsRadio in Pittsburgh early Thursday.
However, McCain talked glowingly of Ridge, a longtime friend who has been a frequent presence at his side during the campaign.
"He's a great American and a great and dear friend, and I rely on him and I have for many years," McCain said.
Asked to hint which way he is leaning, McCain turned -- as he has for days -- to a joke, saying it would be actor Wilford Brimley.
"He's a former Marine and great guy and he's older than I am, so that might work," said the four-term Arizona senator who turns 72 on Friday.
Republicans with ties to McCain's campaign said final deliberations were focused on Romney as well as Minnesota Gov. Tim Pawlenty and Democrat-turned-independent Sen. Joe Lieberman of Connecticut.
Inside GOP circles Thursday, speculation swirled around Lieberman. It was fueled by reports that McCain's advisers had asked for additional detailed information from him, by McCain's close friendship with the 2000 Democratic vice presidential nominee, and by word that Republican operatives had been told to prepare for the possibility of an "unconventional" choice.
GOP strategist Karl Rove late last week encouraged Lieberman to withdraw his name from vice presidential consideration, but Lieberman rejected the suggestion.
A person familiar with the phone call, who requested anonymity because he was not authorized to speak publicly about it, said the suggestion from Rove, President Bush's former top campaign adviser, was laughingly dismissed by Lieberman.
There's been talk among Republican insiders that, should McCain choose Lieberman, he may well declare in his nomination acceptance speech that he will serve only a single four-year term.
GOP operatives say that, combined with putting Lieberman on the ticket, would be a way to show how the ticket would try to work in bipartisan fashion and reinforce McCain's claim that he would put the country above partisan politics. It also could address concerns about his age.
Conversely, hard-core Republicans likely would question why someone who doesn't adhere to GOP orthodoxy would be a heartbeat from the presidency and the prohibitive Republican favorite going into the 2012 election.
That would also raise lame-duck questions and literally touch off the 2012 race as soon as this election ends -- if not sooner.
McCain himself has rejected a single-term pledge as recently as last week.
"No," McCain told Politico. "I'm not considering it."
Picking Lieberman, who supports the Iraq war but breaks with Republicans on most issues, notably abortion rights, would be all but certain to ignite a revolt on the right flank of the GOP heading into the Republican convention in St. Paul and following a week in which McCain's campaign stoked a storyline of division among Democrats in Denver.
McCain, who spoke with the radio station from his home in Sedona, Ariz., told people that he would make no final decision until after he talks with his wife, Cindy. She has been in the country of Georgia this week and had been expected to return late Wednesday.
McCain spent the past several days in Arizona huddling with advisers and working on his nomination acceptance speech.
Ridge, meanwhile, was at his suburban Washington, D.C., home on Thursday. Asked by an Associated Press photographer as he took out the trash if he had any travel plans for the day, Ridge smiled and said he didn't. He went back inside and left in his car soon afterward.
Pawlenty, in Denver to be a McCain surrogate during the Democratic convention, said during a series of TV interviews that all the speculation may be fun and interesting but is foolish. "Most of it turns out to be inaccurate," Pawlenty told Fox News Channel. "Those are questions for the McCain campaign, and I think they are going to make their announcement shortly."
(Copyright 2008 by The Associated Press. All Rights Reserved.)