Sarah Palin, Ted Cruz and other conservative Republicans led a protest on Sunday which tore down barriers at a second world war memorial in Washington and confronted police outside the White House. Palin, the former Alaska governor and 2008 Republican vice-presidential nominee, accused President Barack Obama of using war veterans as pawns in the two-week-old federal government shutdown.

"We are here to honour our vets," she told a crowd at the national mall, which has been fenced off since 1 October. "You look around though and you see these barricades and you have to ask yourself is this any way that a commander in chief would show his respect, his gratitude to our military. This is a matter of shutdown priorities."

Obama could lift the barricades if he wished, she said, adding: "Our veterans should be above politics."

Cruz, a Texas senator and fellow Tea Party darling, accused Obama of targeting the memorial: "He said, 'If you open the memorial I will veto it'."

Thousands of people, accompanied by tractors with blaring horns, converged on the plaza and sang "God bless America". Later some tore down barriers and carried them to the White House, where they dumped them while chanting "shame on you" to police in riot gear.

The protest fuelled a febrile mood as congressional Democrats and Republicans sought an elusive compromise to end the government shutdown and avert an impending default on US debt.

Polls show most Americans blame Republicans for the crisis. Tea Party activists raised the stakes and forced more mainstream Republicans into a corner by linking the fiscal battle to a campaign to repeal the administration's healthcare law.

Sunday's protest attempted to shift blame for the memorial closures, one of the most politically sensitive, on to the White House. It came ahead of a big veterans' rally scheduled for Tuesday, when thousands of former service members are expected in Washington to express concern that the shutdown will disrupt disability payments and other benefits.

"It could be, in worst-case scenario, a suicide spike. Emotional stability drops," Ryan Lamke, a wounded veteran, told CNN. "I mean, we're talking about a population of veterans that are not seeking out the mental health care they so desperately need."

The political battle over memorials follows a separate row over "phony" arrival ceremonies, in which flag-draped coffins of dead military personnel were carried from planes and presented to relatives.

In fact the remains of those killed in Vietnam or the second world war had often arrived weeks or months earlier and been stored in a laboratory run by the Hawaii-based Joint POW/MIA Accounting Command agency. Many of the C-17 cargo planes were towed into position because they can no longer fly, fuelling accusations that the ceremonies, which include bugles and bagpipes, were misleading theatre.

In a statement to NBC, which broke the story last week, the Pentagon said the "arrival ceremonies" would henceforth be known as "honour ceremonies" to avoid confusion.