WASHINGTON - Sarah Palin rumbled through Washington on the back of a Harley as she and her family began an East Coast tour Sunday, renewing speculation that the former Alaska governor would join the still unsettled Republican presidential contest.

Wearing a black leather jacket and surrounded by a throng of cheering fans, Palin and family members jumped on bikes and joined thousands of other motorcyclists on the Memorial Day weekend ride from the Pentagon to the Vietnam Veterans Memorial.

Palin did not mention politics as she visited with participants, but she smiled broadly when many in the crowd urged her to run. When one man asked her if she was running, she smiled and answered: "Don't know."

Palin remains one of the biggest questions for Republicans, who have not yet settled on a front-runner to challenge President Obama's reelection. While many of Palin's likely rivals have worked to build campaign organizations in early nominating states such as Iowa or New Hampshire, she has taken no concrete steps to begin a presidential campaign.

Given Palin's star power, she might be able to wait longer than others. But the clock is ticking, the establishment is not happy with its options and one of the earliest tests of campaign infrastructure, the straw poll in Ames, Iowa, is scheduled for August.

Palin showed no hints she would join the field on Sunday, although she again demonstrated her ability to build excitement and practice the person-to-person, retail politics that she clearly loves.

In heels and black flare slacks, Palin shook hands and posed for pictures with well-wishers. "How do you wear all this leather and stay cool?" she asked one woman.

Just before she; her husband, Todd; and daughters Bristol and Piper rolled from the Pentagon's parking lot, she gave a thumbs-up to a military police officer who asked if he could snap a picture while taking a break from directing traffic. On her hand, the words "justice rolls" were written in smeared ink.

Palin did not take questions from reporters and, in keeping her social-media strategy, offered her thoughts on her political website. "There's no better way to see D.C. than on the back of a Harley!" Palin wrote.

Aides and advisers to Palin were not releasing a schedule for the trip. Throughout the day, there was speculation that Palin might stop in Philadelphia to visit the Liberty Bell, a possibility raised in a report Thursday by the news site Politico. But officials of the Philadelphia police and the National Park Service, which operates the Liberty Bell site, said they had no knowledge of a visit.

Palin's trip set off speculation she would travel up the East Coast and alight in New Hampshire, the state that holds the first nominating primary and a place Palin has not visited since the final days of the 2008 campaign.

Many of Palin's potential rivals were scheduled to visit New Hampshire in the coming week, including another tea-party favorite, Rep. Michele Bachmann of Minnesota. Former Massachusetts Gov. Mitt Romney was expected to make formal his bid Thursday. Former New York Mayor Rudy Giuliani was set to speak at a fund-raiser. Former Utah Gov. Jon Huntsman is spending the weekend working through the state's rural North Country.

Former Minnesota Gov. Tim Pawlenty visited New Hampshire last week, and former House Speaker Newt Gingrich was also out campaigning.