John McCain has scored a huge win tonight in the Wisconsin GOP Primary! With 75% of the vote counted, McCain leads Mike Huckabee 54% - 37%. Here are the details, provided by the Washington Post:

Sen. John McCain logged another victory over former Arkansas governor Mike Huckabee on Tuesday in Wisconsin, where he appeared to be matching his rival among conservative voters, who previously shunned his candidacy.

McCain slogged through 18 inches of snow in 3-degree Wisconsin weather in the morning. But as the votes were counted, the senator from Arizona was already celebrating in Ohio, which will join Texas in holding a primary in two weeks.

"I will be our party's nominee for president of the United States," McCain declared to supporters, acknowledging that outright for the first time and promising to "wage a campaign with determination, passion and the right ideas for strengthening our country."

He immediately turned his fire on Democrats, particularly Sen. Barack Obama (Ill.), dismissing an "eloquent but empty call for change" as "no more than a holiday from history."

In early exit polls, conservatives split evenly. It was a stark improvement for McCain, who has struggled to counter Huckabee's appeal among evangelicals and other GOP base voters. He also won convincingly among Republicans.