President Bush ran into Republican and Democratic resistance to his Medicare reform proposal Wednesday, with even White House allies saying they were confused about what the president intended to propose.

Bush flew more than 1,000 miles round-trip to highlight a top domestic priority: revamping Medicare to give beneficiaries prescription drug subsidies.

"A reformed and strengthened Medicare system, plus a healthy dosage of Medicare spending in the budget, will make us say firmly, 'We fulfilled our promise to the seniors of America,'" Bush said.

But even as he spoke, on Capitol Hill there was growing criticism of Bush's proposal.

Democrats and some consumer groups contended the plan would deny the elderly the doctors of their choice by forcing them into HMOs if they wanted prescription drug coverage.

"His proposal is really a benefit for HMOs," said Rep. Nancy Pelosi, D-Calif.

Even some Republicans weren't enthusiastic, with Sen. Olympia Snowe, R-Maine, saying the "president's focus on ways to reform Medicare could hamper our efforts to pass comprehensive prescription coverage."

Bush, meanwhile, tried to showcase the softer side of his domestic and international agenda, promoting new AIDS money and Medicare changes while visiting a state vital to his re-election.

But he provided no details, and there appeared to be some confusion - even among key Republicans - over his Medicare plan.

"We're not even close to understanding what the president is going to propose," House Majority Leader Tom DeLay, R-Texas, said on Capitol Hill.

Administration officials have said in recent days that the plan would offer the drug benefit to seniors willing to leave the traditional fee-for-service program and join government-subsidized health care plans administered by insurance companies. But on Wednesday, officials were noncommittal about whether the administration would take that route.

Republican Sen. Chuck Grassley of Iowa, chairman of the Senate Finance Committee - which has jurisdiction over Medicare reform - indicated Wednesday he would not support a plan that limited prescription drug coverage to those who agree to leave traditional fee-for-service Medicare.

"We need to strengthen Medicare, first by adding prescription drug coverage that's available for all seniors, not just those that switch into managed care," Grassley said. "All of our changes should be voluntary. If you like what you have now, you should be able to keep it. That means I won't draw lines on drug coverage, regardless of the choice they make."

Perhaps reflecting some of the criticism, Bush aides said Wednesday it could be weeks before specifics are rolled out. Spokesman Ari Fleischer said the administration was still finalizing key elements of the plan.

During his Michigan appearance, Bush renewed his pledge to seek $400 billion over 10 years to change Medicare, mostly to pay for the prescription drug benefit.

Democratic Gov. Jennifer Granholm attended the speech, and Bush thanked her for attending - without mentioning her by name. "I didn't hear too many details about the Medicare proposal," she said.

The White House offered extensive briefings on other voter-friendly issues that Bush laid out Tuesday night. There was also a White House conference call with a senior administration official on Bush's proposal to spend $15 billion over five years to combat AIDS in Africa and the Caribbean.

There was a briefing for reporters on Bush's proposal to spend $1.2 billion over five years to help build the infrastructure to support hydrogen-powered, zero-emission fuel cell vehicles. A senior official wouldn't say whether the administration wants to see the internal combustion engine go extinct, perhaps mindful that the U.S. auto industry calls this state home.

The same briefing also covered the president's proposals for a $600 million increase in federal spending over the next three years to help treat Americans with drug addiction, and $450 million over three years to connect mentors with 1 million children of prisoners and disadvantaged adolescents.

Bush lost Michigan in 2000 to Al Gore and seems determined not to repeat the defeat. His visit Wednesday was his eighth to the state, which will carry a rich trove of 17 electoral votes in 2004.

The White House invited a crowd of health care workers and business leaders, ensuring a raucously supportive crowd.

But outside, protesters thronged the streets of Grand Rapids, most of them demonstrating against possible war.

There were hundreds outside the hospital where he visited with health care workers and a Medicare beneficiary behind closed doors, and hundreds more at several other intersections. They lined virtually the entire route from the hospital to the site of Bush's speech.

Their signs read "I am not convinced" and "greedy people are the real axis of evil."

A cluster of about a dozen people backed Bush with signs that read "Let's Roll - never forget 9/11."

Bush blended tough talk on the war on terrorism into his talk on the "compassion" items in his agenda.

Referring to a firefight Tuesday between U.S. soldiers and Afghan soldiers, he said: "Yesterday, some of them bunched up in parts of Afghanistan. They, unfortunately, met the United States military head-on. Unfortunately for them."

The audience responded with a roar of approving laughter.