WASHINGTON — Midterm elections have often been tame events in America. Not this year.

Today’s congressional elections have been the subject of intense campaigning and relentless press coverage. They have been fought on national rather than local themes, with Democrats focusing on the unpopular war in Iraq and Republicans stressing the need to maintain lower taxes and bolster national security.

“The election is broader than just a referendum on George Bush,” the Democratic National Committee chairman, Howard Dean, whose party is seeking to regain full control of Congress for the first time in 12 years, said. “It is a referendum on the Republican Party, its honesty and its competence.”

Republican Party leader Ken Mehlman said the election “is a pivotal moment in the nation’s history. I am confident we are going to keep our majority, but we ought to engage in a very serious discussion about how to do better after this election is over.”

The stakes are high for President Bush as he heads into the final two years of his presidency. His job-approval ratings are at about 40%, emboldening members of his own party to oppose him on issues from immigration to a Dubai company’s efforts to take over the management of America’s ports. A loss of one or both houses of Congress would weaken him further.

Should Democrats take control of the House or Senate, they would be able to hold investigations of the administration and issue subpoenas.