Democratic Sen. Robert Menendez continues to outpace Republican challenger Tom Kean Jr. in fundraising for the New Jersey seat, amassing $2.58 million from April through June, more than double what Kean raised.

Menendez has $7.4 million cash on hand, said campaign spokesman Matt Miller. He raised slightly more than he did in the first quarter of the year.

Kean, the son of former New Jersey Gov. Thomas Kean, raised $1.1 million for the latest three-month period, $500,000 less than he raised in the first quarter of this year. Kean has $2.25 million cash on hand. The bulk of Kean's second quarter cash came from a June fundraiser hosted by first lady Laura Bush.

Kean campaign spokeswoman Jill Hazelbaker remained confident the state senator will raise enough money to battle Menendez, appointed to the Senate in January by Gov. Jon Corzine to serve out the remaining year of his Senate term. The Kean campaign has not said whether he would dip into his personal fortune to keep pace with Menendez.

Kean makes $46,000 as a state senator but reported having a yearly income of between $88,000 to $263,000 in interest and dividends from various stocks and family holdings, according to his latest financial disclosure form. He also reported total assets of more than $1.5 million. He also has holdings in various Kean family trusts worth tens of millions of dollars.

New Jersey is one of the most expensive states for candidates because ads must be purchased in both the expensive New York and Philadelphia markets to reach voters.