Lou Dobbs, seen in 2007, announced on his show Wednesday night that he would be leaving CNN effective immediately. (Karen Bleier/AFP/Getty Images) Lou Dobbs may have left his anchor chair, but he says he'll keep talking.

The last of the original CNN hosts, Dobbs told viewers on Wednesday that he was quitting his nightly show — effective at the end of the hour — to pursue new opportunities.

What those are is still unclear, though he vowed to be a leader in the "national conversation" to restore "inspiration to our great free society and our market economy."

CNN president Jon Klein announced Thursday that veteran reporter John King will replace Dobbs, moving into the 7 p.m. ET slot with a show about politics beginning early next year.

Dobbs became a lightning rod for criticism following his transition from a business journalist to an opinionated anchor who held forth on such issues as illegal immigration. He was a CNN original, signing on when the cable network started in 1980. For much of that time, he hosted a nightly business broadcast that became one of the most influential shows in the corporate world, and CNN's most profitable show for advertising revenue.

But Dobbs said his worldview changed after the Sept. 11, 2001, hijackings and corporate corruption scandals, and he began to more freely express his opinions. He was particularly persistent in bringing the immigration issue to the fore, winning him both higher ratings and enemies. Latino groups had an active petition drive seeking his removal.

His presence became awkward for CNN, particularly as it began emphasizing reporting and non-opinion shows. He angered management this summer by pressing questions about U.S. President Barack Obama's birthplace after CNN reporters determined there was no issue.

Then came Wednesday night's shock announcement. Seated at an anchor desk in front of a screen with a fluttering U.S. flag, Dobbs gave the day's headlines and then said the network had allowed him to be released early from his contract.

"This will be my last broadcast," he said.

Dobbs said the decision came after months of discussion with Klein, who hailed the host's "appetite for big ideas, the megawatt smile and larger-than-life presence he brought to our newsroom."

"With characteristic forthrightness, Lou has now decided to carry the banner of advocacy journalism elsewhere," Klein said. "We respect his decision."

Dobbs said he was proud of his role in helping to build the first cable news network. He said some leaders in media, politics and business "have been urging me to go beyond my role here at CNN and to engage in constructive problem-solving."

Departure praised by critics

His resignation was hailed by activists who were seeking his ouster.

Tom Saenz, president of the Mexican American Legal Defense and Educational Fund, the leading Latino legal organization, said: "The Latino community can and should celebrate that Lou Dobbs is no longer on CNN."

U.S. Senator Robert Menendez, a Democrat from Dobbs's home state of New Jersey and the Senate's only Hispanic member, called it "addition by subtraction" for CNN.

The research group Media Matters, which had urged CNN to drop Dobbs, also welcomed the news. "This is a happy day for all those who care about this nation of immigrants and believe in the power of media to elevate the political discourse," said Eric Burns, its president.

Dobbs did not return telephone and email messages to talk about his critics.

Although he joined CNN in 1980, Dobbs left the network for two years in 1999 after angrily complaining on air about a decision by then CNN president Rick Kaplan to switch away from his show to a live news event. An internet venture failed and when Kaplan left CNN, Dobbs returned.