The widow of U.S. Sen. Frank Lautenberg gave her public endorsement Monday to Congressman Frank Pallone.

Pallone is one of four Democrats running for the seat left open when Lautenberg died last month.

Bonnie Lautenberg says she considered whom her husband worked with in picking a candidate.

"He and Frank Pallone worked together, on cleaning up Superfund and brownfield sites, holding polluters accountable, stopping ocean dumping and protecting New Jersey's beaches," she said. "When my husband needed help from the House of Representatives on an environmental issue, he always knew what to do -- he called Frank Pallone."

Polls say Pallone faces a steep challenge in next month's primary since Newark Mayor Cory Booker has a big lead.

In an appearance Monday with Pallone, Bonnie Lautenberg took a shot at the nationally known Booker.

"Being great on TV and raising money outside the state doesn't mean that you're going to be the most effective in the United States Senate. You have to look at how they've done in their current jobs," she said. "And I know that Frank Pallone has done a really good job representing his district.

Other Democrats running in the Aug. 13 primary are Congressman Rush Holt and Assembly Speaker Sheila Oliver.

The winner of the Democratic primary is likely to face Steve Lonegan, the former mayor of Bogota, on the Republican side in the Senate election Oct. 16.