A hard-fought U.S. House election in California that could offer clues about voter sentiment before November’s midterm election highlights a busy day of voting in eight states on Tuesday.

Democrat Francine Busby and Republican Brian Bilbray are running hard in a special election in a conservative district north of San Diego to replace former Republican congressman Randy Cunningham, who is now in prison for taking bribes.

With congressional Republicans and President George W. Bush slumping in the polls, the California race is being closely watched for signs of a political shift toward Democrats just five months before voters decide control of Congress.

Montana, Alabama, Iowa, New Jersey, Mississippi, New Mexico and South Dakota also hold primaries to select candidates for the November elections, when all 435 House seats, as well as 33 Senate seats and 36 governorships, will be up for grabs.

In other key races, Montana Democrats choose a challenger to embattled Republican Sen. Conrad Burns, California Democrats pick a rival for Republican Gov. Arnold Schwarzenegger and both parties choose a nominee for governor in Alabama.

Democrats must pick up 15 House seats and six Senate seats to regain control in each chamber, giving them the power to set the legislative agenda and more effectively challenge Bush.

A win in the California House race would be a huge first step for Democrats, who have been encouraged by Busby’s showing in a district that normally favors Republicans.

Both parties have poured millions of dollars into what has become a rough campaign, and Republicans launched a radio ad to capitalize on comments on immigration by Busby.

While talking to a mostly Hispanic audience at a senior center last Thursday, Busby said: “You don’t need papers for voting, you don’t need to be a registered voter to help.”

Busby later said she misspoke but Bilbray and Republicans said she was encouraging illegal immigrants to help her.

An independent candidate, William Griffith, could siphon votes from Bilbray, a former congressman who has been accused by conservatives of being too moderate on social issues.

The winner of the special election will serve only to the end of Cunningham’s term and must run again in November.

(Additional reporting by Marty Graham in San Diego)

© Reuters 2006