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A billboard company has blocked a national pro-life group's latest effort to post ads linking a congressional candidate to abortion funding – in the wake of a similar 2010 effort that resulted in a defamation lawsuit.

The Susan B. Anthony List ads argue Rep. Joe Donnelly, D-Ind., supports taxpayer-funded abortions because he voted in favor of President Obama’s health care overhaul legislation.

The group two years ago contracted with the same firm, Lamar Advertising, to post similar ads against then-Rep. Steve Driehaus, an Ohio Democrat who lost his re-election race and sued the Susan B. Anthony List. Lamar declined to accept the Driehaus ads under pressure.

The group calls Driehaus' suit “frivolous,” and it argues Lamar Advertising's recent decision not to run the anti-Donnelly ads on its billboards raises First Amendment questions.

“This continued assault on our free speech hits at the basic freedoms groups and individuals in this country enjoy, to criticize their elected officials and to demand better representation,” said group President Marjorie Dannenfelser. “Under ObamaCare, taxpayers are forced to fund abortion. Yet despite this growing consensus, the free speech of the SBA List continues to be chilled.”

The Susan B. Anthony List and its connected political action committee are dedicated to electing candidates and pursuing policies that will reduce and ultimately end abortion, according to the group’s mission statement.

In the ongoing federal lawsuit, Driehaus claims the group "disseminated lies,” as well as cost him his job and “loss of livelihood.”

Hal Kilshaw, Lamar Advertising's vice president of government affairs, told FoxNews.com the company won’t raise the billboards with the abortion-funding copy because it was already threatened by Driehaus with criminal prosecution.

“We’re just not doing that again,” he said. “It was a legal nightmare.”

Kilshaw said the company would consider other advertising from the group, “but we’re just not running that copy.”

Driehaus’ original complaint cited statements made about his record on abortion. Among them was the set of billboards the group planned to erect. He first filed a complaint with the state election board over the billboards, which did not go up, claiming they broke a state law prohibiting false statements. That battle continued until after the election when Driehaus dropped the complaint and instead filed the defamation suit.

Driehaus has claimed he's going after the pro-life group because they crossed the line and lied.

"The First Amendment is not and never has been an invitation to concoct falsehoods aimed at depriving a person of his livelihood," his original complaint stated.

Driehaus' attorney Paul De Marco said at the time that liars can't "hide behind the First Amendment."

While libel and defamation law protects most speech when it comes to public officials, it does not necessarily protect false speech.