"Nineteen individuals have served both in the National Guard and as president of the United States, and I am proud to be one of them," Mr. Bush told the National Guard Association of the United States conference in Las Vegas, Nev.
Members of the Guard are fighting in Afghanistan and Iraq, and helping recovery efforts after Florida hurricanes, Mr. Bush said. "I am proud to be their commander in chief, and I respect and honor all of those who serve in the United States Armed Forces — active, Guard and Reserve."
Mr. Bush made no mention of the election-year tempest over his Vietnam-era service in the Guard. But the Democratic National Committee sought to fuel the controversy by releasing a nearly three-minute video accusing Mr. Bush of using family connections to get into the Guard and out of the Vietnam War.
Newlast week suggest Mr. Bush ignored a direct order from a superior officer to take a physical exam and lost his status as a Texas Air National Guard pilot in the 1970s because he failed to meet military performance standards and did not get the physical.
Questions have been raised about the authenticity of the documents obtained by an unidentified source by CBS News. The news organization is standing by its story.
The Pentagon's reliance on the National Guard and Reserve grew quickly after Mr. Bush authorized a partial mobilization of reserve forces in the days following the Sept. 11, 2001 terrorist attacks, and they currently comprise about 40 percent of the entire U.S. force in Iraq.
As of last week, there were 165,000 National Guard and Reserve troops on active duty in support of the war on terrorism, including those providing extra security in the United States.
The combat duty that some Guard units are doing in Iraq is their first since World War II, and they are suffering large numbers of casualties. At least 175 Guard and Reserve troops have died in Iraq since the invasion was launched in March 2003 — more than a third of those in the past five months.
Mr. Bush said he recognized those difficulties, and said his administration was working to ease their burden.
"I know this time of call-ups, alerts, mobilizations, and deployments has been difficult for Guard members and their families and employers," he said.
"We are working to provide you at least 30 days notification before you are mobilized, so you have time to make arrangements," said Mr. Bush. "We are working to give you as much certainty as possible about the length of your mobilization — you deserve to know when you can expect to resume civilian life."
The Pentagon also was trying to minimize the number of deployment extensions and "repeat mobilizations," he said.
Democratic presidential candidate Sen. John Kerry, a decorated Vietnam veteran, addresses the same group Thursday.
Mr. Bush holds a commanding lead over Kerry among veterans and their families. An AP-Ipsos poll last week found Mr. Bush was the choice of 58 percent and Kerry 38 percent. In the poll, veterans and their families said Mr. Bush was stronger and more honest than Kerry.
On Monday, first lady Laura Bush said she thought the documents obtained by CBS were probably fakes.
"You know, they probably are altered and they probably are forgeries, and I think that's terrible, really," she told Radio Iowa in an interview.
Mr. Bush spoke to the National Guard following a morning campaign rally near Denver, where he was joined by football icon John Elway.
During a 50-minute speech, Mr. Bush touted his health-care plan and the economy. He said Colorado's economy, with a 5.1 percent unemployment rate, was improving.
"This economy is strong, and we're not turning back," he said to cheers from audience.
Elway, the quarterback who led the Denver Broncos to two Super Bowl victories, praised Mr. Bush in football terms. "This man knows how to make the right calls when the pressure is on," Elway said.
Two hecklers disrupted the president's speech, and the crowd shouted them down with chants of "Four more years!" As the protesters were removed, one shouted, "Get outta here!" and the other held up the two-finger peace sign.
Kerry was campaigning Tuesday in Milwaukee, Wisconsin, where he promised a group of senior citizens that he would ease the financial pinch caused by the escalating price of doctors, hospitals and medicine as it outpaces annual increases in Social Security benefits.
"Seniors are finding things more and more out of reach as the expenses go up but their ability to meet it does not go up," Kerry said. President Bush worsened the squeeze on older voters, Kerry said, by crafting a Medicare prescription drug benefit that won't lower drug costs, helping drive up premiums for the Medicare program.
"George Bush has had four years to lead, four years to give America a direction, four years to bring corporate America to the table, and the health care industry, and say we've got a problem," he said.