President Bush and leading Republicans are increasingly charging that Democratic presidential nominee John F. Kerry and others in his party are giving comfort to terrorists and undermining the war in Iraq -- a line of attack that tests the conventional bounds of political rhetoric.

Appearing in the Rose Garden yesterday with Iraq's interim prime minister, Ayad Allawi, Bush said Kerry's statements about Iraq "can embolden an enemy." After Kerry criticized Allawi's speech to Congress, Vice President Cheney tore into the Democratic nominee, calling him "destructive" to the effort in Iraq and the struggle against terrorism.

It was the latest instance in which prominent Republicans have said that Democrats are helping the enemy or that al Qaeda, Iraqi insurgents and other enemies of the United States are backing Kerry and the Democrats. Such accusations are not new to American politics, but the GOP's line of attack this year has been pervasive and high-level.