Democrat Dennis Kucinich (search) on Monday criticized presidential front-runner John Kerry (search) as being too similar to President Bush on Iraq and said voters must be given a "clear and convincing choice."

Kucinich, a congressman from Ohio, pointed to his third-place finishes in Democratic caucuses over the weekend as signs that his campaign was starting to resonate with voters.

Speaking at a National Association of Hispanic Journalists' (search) forum, Kucinich said the Iraq war will be the instrumental issue in the November election. He criticized Bush for starting it and took aim at Kerry, a Massachusetts senator who voted for the congressional resolution authorizing the war.

"Senator Kerry voted for the war. Senator Kerry supports the occupation. Senator Kerry supports sending another 40,000 troops to Iraq," Kucinich said. "I'm wondering if the people of this country are ready to trade a Republican war for a Democratic war, because that's exactly where we're headed right now."

He advocated for United Nations involvement in Iraq and noted that he had promoted a plan to get the United States out of the country.

Kerry has said he supported the war based on faulty U.S. intelligence. He opposed an $87 billion aid package for Iraq and Afghanistan and supports increasing the number of Americans in uniform worldwide by 40,000.

Kucinich's third-place finishes in Maine and Washington state over the weekend were far behind those of Kerry, who easily carried both states. Former Vermont Gov. Howard Dean finished second in each.

But Kucinich said his campaign still has the potential to change the race because he offers voters an alternative and that the Democratic nomination is not locked up.

"That's why I intend to go through all the way to the convention, that's why I believe it's going to be very difficult for anyone to go into that convention with 50 percent of the delegates," Kucinich said. "Is it possible? Yes. But I don't think it's a sure thing. You could still see the selections change."

And only someone with positions far from the current administration can replace Bush, Kucinich said.

"He still maintains an enormous amount of support among the American people, and it's not going to be that easy to dislodge him," Kucinich said. "Only if there's a clear and convincing choice given to the American people on critical issues ... are we going to able to be assured that this president will be defeated."