President George W. Bush has promised to implement the recommendations of a bi-partisan presidential panel that called for sweeping changes to the system.
The high-profile veterans group Votevets.org warned the White House not to drag its feet after Wednesday's recommendations.
Other veterans' groups weighed in Thursday to hold Bush to his word. Paul Rieckhoff, an Iraq veteran and executive director of the Iraq and Afghanistan Veterans of America (IAVA), urged the nation not to let the issue drop.
"We urge the news media and American combat veterans of all generations to ensure that the recommendations of this report are not buried in the back pages of our nation's newspapers," he said.
"We call on the president and Congress to build on this progress and ensure these recommendations are enacted quickly," said another IAVA representative, Todd Bowers.
Votevets.org was reacting to earlier statements by White House spokesman Tony Snow.
He had said the recommendations would not be implemented immediately, but merged into ongoing plans to improve health care for returning soldiers.
"It is unfortunate that the White House is signaling that they don't view this as an urgent issue," said group founder Jon Soltz.
"With more and more troops coming back from Iraq with severe physical and mental injuries, the time to fix this problem is now, not months or years from now."
Bush set up the panel after news reports in March revealed that wounded war veterans seeking health benefits endured bureaucratic nightmares at Walter Reed, the top US army hospital.
The Washington Post also found severely wounded soldiers living in a building with moldy walls and infested with mice and cockroaches.
The revelations provoked an emotional response from a nation with tens of thousands of troops deployed abroad. More than 27,000 US soldiers have been wounded in Iraq and in Afghanistan.
The panel called for measures to help veterans cut through bureaucracy to get aid and called for active steps to treat post-traumatic stress disorder -- a psychological condition often downplayed in the macho military world.
It also recommended measures to strengthen support for the families of the wounded soldiers.
Veterans groups skeptical of the administration's commitment to a speedy overhaul are not letting up the pressure.
The group accuses the government's Department of Veterans' Affairs (VA) of violating soldiers' constitutional rights by subjecting them to poor care and excessive bureaucracy.
It also accuses the department of cheating veterans who suffer from post-traumatic stress disorder by making them own up to pre-existing mental problems in order to avoid compensating them.
Some 8,000 US troops are in Afghanistan taking part in Operation Enduring Freedom.
It was launched in October 2001 against forces of the ousted Taliban regime and Al-Qaeda, the network blamed for killing thousands in the attacks on the United States on September 11, 2001.
In Iraq, where 160,000 US troops are deployed, eight more were killed Thursday.
This took the US military's losses in Iraq since the March 2003 invasion to 3,642, according to an AFP count based on Pentagon figures.
The group Veterans for Common Sense launched a class-action lawsuit Monday on behalf of hundreds of thousands of Iraq and Afghanistan war veterans against the government for providing them with deficient medical and financial support.
Paul Sullivan, executive director of the 11,500-strong group, called for the heads of the department to quit, though he conceded the panel's recommendations were "going in the right direction."
But he was scathing about the US Department of Veterans Affairs.
"Even if VA receives additional money and even if VA has new policies to streamline the process, we must remove the incompetent leaders at VA who have crashed VA on Iraq," he told AFP.
The department's secretary, Jim Nicholson, announced his resignation last week but is not due to leave until October. Sullivan called for him to leave immediately.
"This issue is not about funding. It is not about policies. It is about our veterans," he said. "The Bush administration has failed our veterans and there must be accountability for the political appointees who failed."