By Tabassum Zakaria GRAND RAPIDS, Mich., Sept. 14 (Reuters) - Vice President Dick Cheney on Friday accused critics of the administration's war strategy of ignoring the bloodshed and chaos he said would follow a premature U.S. troop withdrawal. Speaking shortly after President George W. Bush announced a limited withdrawal of about 20,000 U.S. troops by next July, Cheney pounded home the argument that the United States must stay in Iraq for the long haul to combat terrorism. "In all the calls we've heard for an American withdrawal from Iraq, these negative consequences haven't really been denied, they've simply been ignored," he said. Anti-war Democrats and some Republicans have called for a timetable for a full withdrawal, which Bush has resisted. His new plan would leave more than 130,000 troops, roughly the same number on the ground before he added an additional 30,000 to help secure Baghdad and Anbar province. Bush's announcement on Thursday night failed to appease Democrats who complained he was simply repackaging what they called a failed strategy instead of offering a new direction in the unpopular war. "Back in Washington we'll continue to have debates about Iraq and broader national security policy, as we should," Cheney said. "Tough work lies ahead." But, he added, the evidence from Iraq was "beyond question: The troop surge has achieved some solid results, and in a relatively short period of time." Cheney returned to well-hammered Bush administration themes, warning of dire consequences of pulling troops out of Iraq too early and the dangers of extremist groups like al Qaeda, which he called "the main enemy we face." If U.S. and coalition forces left Iraq before Iraqis could defend themselves, moderates would be "crushed," extremists would push the country into "chaos," and competing factions including groups backed by Iran "would unloose an all-out war, with the violence unlikely to be contained within Iraq," Cheney said. "The ensuing carnage would further destabilize the Middle East and magnify the threat to our friends throughout the region," he said.