WASHINGTON -- As speculation mounts, Democrat Barack Obama and Republican John McCain are narrowing their choices for vice presidential running mates with their nominating conventions just weeks away.

Current and former governors and senators seem the most serious contenders, though most of those mentioned are playing coy about any discussions with either campaign.

The choices were expected to carry special weight with voters in this election: McCain would be the oldest person elected to a first term as U.S. president and Obama may be looking for a more experienced running mate since he has just four years on the national political stage.

With the Democratic national convention less than a month away, there were growing indications that Sen. Hillary Rodham Clinton -- once seen as a natural choice for Obama after he defeated her in an extended primary battle -- has been ruled out or slipped to near the bottom of the Illinois senator's short list.

Campaign watchers now are looking to Virginia's Democratic Gov. Tim Kaine, who on Tuesday refused to confirm media reports that he has given the Obama campaign his financial records for review.

"I'm just not going to talk about my conversations with the campaign," he said after appearing on a Washington radio station.

McCain has likewise kept his decision-making under tight wraps and potential running mates have been just as evasive.

Minnesota's Republican Gov. Tim Pawlenty said he has decided to stop answering questions about a spot on McCain's ticket because of all the gossip.

Among others believed to be getting close looks were Indiana Sen. Evan Bayh, Delaware Sen. Joe Biden and Kansas Gov. Kathleen Sebelius for Obama; and former Massachusetts Gov. Mitt Romney and former Ohio Rep. Rob Portman for McCain.

Obama met Tuesday with top aides and his search committee in Washington for the second time in as many days, and at least the third time this month.

He told NBC television on Sunday he was going to pick "somebody with integrity; I'm going to want somebody with independence, who is willing to tell me where he thinks or she thinks I'm wrong; and I'm going to want somebody who shares a vision of the country -- where we need to go. That we've got to fundamentally change not only our policies but how our politics works; how business is done in Washington."

That comment casts doubt that Obama would choose Clinton, who has spent more than a decade in Washington as a first lady and New York senator. During the primaries, Obama portrayed her as the ultimate Washington insider while suggesting he offered a fresh approach, above partisanship.

Even so, Obama told the network: "I've said consistently that I think Hillary Clinton would be on anybody's short list."

For his part, McCain gave away even less during a Monday interview with CNN television.

"I will announce it just as soon as the process is completed," the Arizona senator said, adding he was vetting both men and women.

On the campaign trail, both candidates were focusing on the economy -- the No. 1 issue on voters' minds -- after sparring for most of the last week over the war in Iraq as Obama traveled to the Middle East and Europe.

On Wednesday, Obama planned to emphasize economic security for middle-class Americans at town hall meetings in Springfield and Rolla, Missouri -- a battleground state in the November election where polls show a tight race.

McCain intended to talk about tax cuts for small businesses and energy conservation measures during a visit to a company in Aurora, Colorado, that sells and rents machines used in heavy construction, mining and waste handling.

Obama spoke with both Treasury Secretary Henry Paulson and Federal Reserve Chairman Ben Bernanke on Tuesday about the faltering economy, part of his effort to refocus his campaign on domestic issues after last week's foreign trip.

Obama spokesman Michael Ortiz said the senator and Bernanke discussed the outlook for consumers and businesses, as well as the effect of rising home foreclosures on families nationwide. They also talked about the "strengths of Fannie Mae, Freddie Mac and other financial institutions," Ortiz said.

Obama called Paulson as he rode to a meeting with Pakistan's new prime minister, the campaign said.

A campaign statement said Obama asked how the Treasury Department planned to use its new authority with mortgage giants Fannie Mae and Freddie Mac and whether the government had the tools it needs to address the challenges in the banking industry. As part of the government's effort to provide mortgage relief to hundreds of thousands of homeowners, Paulson has sought emergency power to rescue lending Fannie Mae and Freddie Mac.

Congress approved a housing plan last week that would provide relief for 400,000 homeowners who cannot afford their payments by allowing them to refinance their mortgages with more affordable, government-backed loans. President George W. Bush has promised to sign the package into law.

In a day of meetings in Washington, Obama also met with Pakistan's new leader, Prime Minister Yousuf Raza Gilani.

At a fundraising luncheon, he said he told Gilani "the only way we're going to be successful in the long term in defeating extremists ... is if we are giving people opportunities. If people have a chance for a better life, then they are not as likely to turn to the ideologies of violence and despair."

Obama later told members of the House Democratic caucus that that as president he would order his attorney general to carefully review all of President George W. Bush's executive orders and expunge any that "trample on liberty," several lawmakers said.

Presidents, as head of the executive branch of government, issue such orders to direct operations of executive branch agencies, like the Justice Department and the CIA. For example, President Bush used an executive order last year to breathe new life into the CIA's controversial terror interrogation program that allowed harsh questioning of suspects.

McCain, meanwhile, received welcome health news Tuesday. A biopsy of a small patch of skin removed from the Republican candidate's right cheek showed no evidence of skin cancer, doctors said Tuesday.

The Arizona senator, who suffered severe sun damage from his 5 1/2 years in North Vietnamese prison camps, gets an in-depth skin cancer check every few months because of a medical history of dangerous melanomas. He has survived three bouts of melanoma that included four lesions.

McCain on Tuesday held a town hall meeting with voters in Sparks, Nevada. He tried to strike a balance between the independence he boasts of and his avowed conservatism.

"As many of you know, I've been called a maverick, someone who marches to the beat of his own drum," McCain said proudly.

The Arizona senator insisted anew he would not raise taxes if elected president and vowed to appoint judges like Samuel Alito and John Roberts, conservatives named to the Supreme Court by Bush. But McCain did not back off his belief in global warming and support of alternative energy development, which is the centerpiece of his plan to revitalize the U.S. economy.