PORTLAND (AP) – Declaring that his campaign has “no place for the politics of personal destruction,” Democratic Senate candidate Tom Allen vowed Monday to denounce any third-party attack ads that personally target Republican incumbent Susan Collins.

The Collins campaign welcomed Allen’s pledge but went a step further, proposing an agreement to order their respective national parties to not run any television or radio ads in the Maine Senate race.

Allen told a news conference that because his campaign is barred by law from having contact with outside political groups that support his candidacy, he decided to go public with his request that they refrain from placing any ads that mention Collins by name or include her likeness.

“If you plan to attack Senator Collins, don’t,” Allen said. “That won’t help your cause and it has no place in the conversation I intend to have with the voters of Maine,” he said.

The Collins campaign welcomed Allen’s pledge but questioned why he remained silent last summer while moveon.org and and other third-party allies ran nearly $1 million worth of negative ads aimed at the senator.

“He had ample opportunity over the past year to come forward and do the right thing and denounce the myriad of advertisements that were run against Senator Collins,” said Felicia Knight, deputy campaign manager. She said Allen failed to criticize outside groups, even when they ran an ad that featured solicitations with Collins’ teeth blacked out.

Allen brushed aside such criticism, saying “last summer was last summer” and at that time “we were getting our campaign up and running.”

Collins has always discouraged outside groups from placing negative ads on her behalf, Knight said. She said that if Allen tells the Democratic Party not to run any ads during the campaign, Collins would make the same demand of the Republican Party.

“An arrangement such as that would be a huge step toward ensuring that the campaigns control the tone and the content of the television ads in this campaign,” Knight said.

Allen’s camp rejected the offer, saying it would accept positive messages from the Democratic Senatorial Campaign Committee or any other third parties.

“My sincere hope is that all third parties – those who favor Senator Collins and those who favor me – will limit their television and radio advertising to positive messages about their favorite candidate,” Allen said.

In any event, neither side is likely to be strapped for cash to buy ad spots.

The latest campaign finance reports show that Collins has raised $5.5 million and Allen $3.7 million, a record total of $9.2 million, and that Collins had $4.5 million in hand to Allen’s $2.7 million.

Even if the candidates denounce outside attack ads and ask they they be taken off the air, there is no guarantee that the groups bankrolling them will agree to do so.

Such was the case last month in North Carolina, where the state Republican Party rebuffed John McCain’s request not to run a TV ad showing Barack Obama and his controversial pastor.

AP-ES-05-19-08 1438EDT