Sununu has healthy fund-raising advantage over Democratic opponents

US Senator John E. Sununu, a New Hampshire Republican, has nearly triple the amount of campaign cash than his closest Democratic opponent for his 2008 re-election bid.

The race is expected to be one of the most closely watched and most expensive in the country, experts in both parties say.

Campaign finance records provided to the Globe show Sununu raised $540,397.61 in the first three months of the year. This means Sununu currently has roughly $1.25 million cash on hand.

So far, two Democrats are challenging Sununu. Former congressional candidate Katrina Swett raised $462,000 for the period and has $443,000 cash on hand. Portsmouth Mayor Steve Marchand raised $97,000 and has $86,000 cash on hand.