As the end of his national book tour nears, Al Gore is also nearing a self-imposed, mid-December deadline to decide if he'll run for president in 2004.

But before the former vice president even opens his mouth, a surge of media speculators are guessing that Gore may ultimately sit it out.

Sales of Joined at the Heart, co-authored with wife Tipper, have been slow: It's ranked 4,041 on Amazon.com and 1,385 on Barnes and Noble.

Gore aides disagree but some Democrats call it a sign of apathy toward the former vice president.

"If he's on a book tour and people aren't even buying his book, maybe it tells him something. But is he able to look himself in the mirror and admit that?" a 2000 Gore backer asked in Thursday's New York Post.

Book tours are a staple of modern presidential campaigns, and like that, Gore has also been wooing donors and blasting White House policies.

"The best thing they could do is completely scrap the entire economic plan and start over again from scratch," Gore said in a summertime speech.

Gore has blasted Bush on the economy, the war on terror and action against Iraq in a string of left-leaning speeches that certainly make him sound like a candidate.

But some Democrats worry that by shifting left, Gore is alienating critically important independent and swing voters who decide elections.

And now that Massachusetts Sen. John Kerry is officially exploring a White House bid — filing papers to launch an exploratory committee on Wednesday — Gore can expect mounting criticism from the Kerry camp and other potential rivals if he decides to go forward.

Washington Post columnist Richard Cohen compares Gore to Adlai Stevenson, who lost twice in the 1950s to Dwight D. Eisenhower, whom Cohen compared favorably to President Bush.

Gore aides and insiders say some days he sounds eager to run but on others he seems uncertain. Publicly, he's undecided.

"I haven't ruled it out, but I am going to wait until the holidays and make a decision with my family," Gore said Thursday at a Chicago book signing.

Eldest daughter Karenna — who spoke at the 2000 convention — is urging her dad to give it another go.

Tipper Gore offered enthusiastic encouragement over the summer, but in recent weeks has told friends that she will support whatever decision her husband makes.

"He's a very good seller of books," she said Thursday.

The latest New York Times poll suggests 55 percent of Democrats want a new candidate, compared to only 33 percent who would nominate Gore again.

But in a hypothetical primary, a Gallup poll shows Gore with 38 percent, more than triple any of his potential Democratic opponents.

At the conclusion of his book tour, Gore has one more planned public appearance before making and eventually announcing his decision. He will host Saturday Night Live on Dec. 14.

Fox News' Carl Cameron contributed to this report.