WASHINGTON (CNN) -- Republican presidential candidate Sen. John McCain is betting heavily on the New Hampshire primary, hoping his muscular approach to national security will appeal to the state's Republican voters.
Sen. John McCain campaigns in Concord, New Hampshire, last week.
To win in the New Hampshire primary, McCain needs the support of the Independent voters who helped him win in 2000, many of whom are wary of his support of the Iraq war.
"Most Republicans support the war. Most Independents don't," CNN senior political analyst Bill Schneider said. "Any gains McCain makes with Republicans on the war are likely to be negated by losses among Independents."
If he fails to strike that delicate balance the Arizona Republican may have to cash in his chips and go home in January.
McCain's position as the national security candidate strengthened Monday with the endorsement of Tom Kean, the former New Jersey governor and co-chairman of the 9/11 commission.
Kean said he decided to endorse McCain, in large part, due to McCain's national security credentials.
"First and foremost, John McCain understands the dangers of the terrorist threat that continues to affect every single one of us every single day," Kean said during an event in Boston, Massachusetts. "We better have a president who is ready to take the job, and ready to take the helm, and ready the day he takes office. John McCain is ready to be president." Watch Kean describe how McCain has kept Americans safe »
"This is the first time in 20 years I've endorsed anyone on the national level," Kean added. "Usually I stay out of these things. This is an endorsement, frankly, of conscience. I frankly couldn't sit by and not endorse this man."
Speaking at Monday's event, McCain, a decorated Vietnam veteran and four-term senator, put his national security experience front and center.
"I have 20 years of experience on national security issues and I respect the values and principles, but I will try to convince the American people I need no on the job training. I know these leaders; I've been in their countries; I understand these challenges better ... than those who are seeking the nomination of my party or the other party."
It was also announced Monday that McCain will lead a small congressional delegation to Iraq Thanksgiving week to have Thanksgiving dinner with U.S. troops, a McCain adviser told CNN.
A CNN/WMUR poll out Monday shows McCain in second place among likely Republican New Hampshire primary voters with 18 percent, trailing front-runner Mitt Romney, the former Massachusetts governor, with 33 percent.
McCain moved into second place when former New York Mayor Rudy Giuliani lost 8 points from the previous month, dropping from 24 percent in September to 16 percent in October.
The poll suggests McCain's strength on national security issues, and particularly the war in Iraq, could provide an opening to move up on Romney and Giuliani, the national front-runner.
Forty-two percent of New Hampshire Republican primary voters, according to the poll, believe McCain is the best candidate to handle Iraq.
"The war in Iraq remains the top concern among GOP primary voters," CNN polling director Keating Holland said. "McCain beats Romney as well as Giuliani by nearly a three-to-one margin on the war."
But McCain's support could also turn off New Hampshire Independents. Independents, who are free to vote in either the Republican or Democratic primaries, are more likely to oppose the Iraq war and may not turn out for McCain like they did in 2000, the year he beat then-Texas Gov. George Bush in the Republican primary.
Furthermore, the war in Iraq is declining in importance for New Hampshire voters, just as an issue that may be a liability for McCain -- immigration -- is rising in importance.
The comprehensive immigration reform legislation McCain co-sponsored this summer drew the ire of many conservatives in his party, and Romney has been taking a tough stance on the issue.
Plus, McCain may have to overcome a mental barrier in the minds of voters: At the moment, many New Hampshire voters don't expect him to be the nominee.
"New Hampshire Republicans are beginning to see a two-man race for the nomination: Romney v. Giuliani," Schneider said. "Only 8 percent believe McCain is a likely national winner. That could be holding his numbers down in New Hampshire -- a state he has to win."
The CNN/WMUR poll was conducted by the University of New Hampshire between Wednesday and Sunday. Pollsters surveyed 404 Republican voters for the survey, which had a sampling error of 5 percentage points. View the poll results »
For McCain, concentrating on New Hampshire may come at the expense of a strong showing in another early voting state, Iowa.
As reported in the Sunday New York Times, McCain associates said he would not spend much time in the Iowa before the caucuses on January 3.
McCain may be putting more effort into a strong showing in New Hampshire because his support in Iowa is relatively weak.
According to a KCCI/KCRG poll conducted November 12-14, McCain is running fifth in the state, at 6 percent, far behind front-runners Romney, at 27 percent, and former Arkansas Gov. Mike Huckabee, at 28 percent.
But asked by reporters Monday if he was moving out of Iowa to focus on New Hampshire, McCain answered, "That's not true. We are not moving out of Iowa."
"We are just going to work harder in all three [early voting] states: New Hampshire, South Carolina, and Iowa." E-mail to a friend
CNN's John King and Chris Welch contributed to this report.