My estimate is that no more than 20% of the population places any kind of priority on sending men to Mars. Since about 5% of those want to send astronauts to visit the "Face" on Mars, that leaves about 15%.

If the demand was as great as the Mars Nuts claim, the elected representatives would have been started the program a long time ago. Since they have not, let us look closely at the polls here.

"I have no link for this one only the front end of the poll seems to still exist not the results...
The first week of Pathfinder and Sojourner being on Mars there was an online poll conducted by CNN which asked is "Do you think Mars exploration is a worthwhile investment?" and when I took it the numbers were something like 16% NO and 84% YES this was during July 6, 1997..."

No doubt there's demand for ROBOTIC exploration - but that does not mean there's a demand for manned Mars flight...

"Public Supports Exploration

"Sixty-eight percent of the public believe it was "worth it" to send humans to explore the Moon in the Apollo Program, according to a July 1997 poll by CBS News. Fifty-four percent favor "sending astronauts to explore Mars." In a Roper poll (7/11/97), 62 percent of the public said they would support "the United States sending astronauts to explore Mars."

Again, is that some day or right now, and exactly how much would the public be willing to spend... and we have no information on how either poll was taken...

"Seventy-two percent of Americans want some kind of Mars-exploration program, a new SPACE.com/Harris Interactive Poll has found."

You have to know who was sampled and how - note that this poll was of online users, which is to say techies, and this means that it does not reflect the population as a whole - this is about as effective as asking the Mars Nuts here at Habitable Zone their opinion:

"THE POLL, WHICH WAS CONDUCTED ONLINE, surveyed 2,353 people that are a part of the Harris Interactive online database. The figures were weighted by age, region, gender and race to represent the U.S. The poll has a 2-percent margin of error, according to Harris.

The next poll shows the same kind of sampling bias:

"Poll: Kids look forward to rock climbing on Mars
"More than 2,600 youngsters took part in the online poll, released Thursday by the organizers of Space Day, an annual event designed to bolster interest in science, math and space among youths. "

Now there's an unbiased sample of adults if I ever heard of one.

The next poll is pretty accurate, but note that no one was sked directly about manned flight to Mars:

Gallup poll shows strong public support for NASA
Posted: Tue, Feb 18, 2003, 7:04 PM ET (0004 GMT)

A poll published this week by the Gallup Organization shows that the American public is still strongly supportive of NASA and the shuttle program despite the Columbia tragedy. The poll, commissioned by CNN and USA Today, found that 25% of respondents wanted NASA's funding increase, while 49% believe the agency's funding should remain at currently levels. Only 17% said the agency's budget should be cut. That level of support was somewhat higher than the last poll conducted by Gallup in December 1999, after the failures of the Mars Polar Lander and Mars Climate Orbiter spacecraft. The same poll showed that 52% of people believed that NASA should concentrate on manned missions, versus 37% who preferred unmanned missions; those figures were similar to the last poll from November 1998. Seven percent of people said NASA should concentrate on both, even though that was not one of the options given in the poll question. The poll also revealed that 31% of people would be interested in flying on the shuttle, down only slightly from when the question was last asked in 1991. Men were more likely to support increased funding for NASA or be willing to fly on the shuttle than women. The poll results were based on a survey of 1,000 adults in the US February 7-9.