Updated 4:13 p.m.

Rep. Ed Pastor (D-Ariz.) announced Thursday that he will be retiring after his current term, setting off what could be a widespread battle to replace him.

Rep. Ed Pastor (D-Ariz.), left, photographed with Housing and Urban Development Secretary Shaun Donovan. (Charlie Leight/AP)

The 11-term lawmaker made the announcement via Facebook: "After 23 years in Congress serving the people of Arizona, I have decided that I will not seek re-election this year. It has been a great honor and experience, but it is time for me to close this chapter of my life and start a new one," he said. "I want to thank everyone who has assisted me and supported me throughout my career. Thank you very much for all of your support."

Pastor's seat is safely in Democratic hands and is one of the few where President Obama improved his win percentage from 2008 to 2012. In 2008, Obama won with 65 percent of the vote; in 2012, he earned 72 percent.

As the news of Pastor's retirement was announced Thursday afternoon, state Rep. Ruben Gallego (D) announced via Twitter: "I am in for Congress." An Iraq war veteran, he is seen as a rising star in Arizona politics.

But several others Democrats are also eying the race and many have been waiting decades for the chance to run. Even now-Rep. Kyrsten Sinema (D-Ariz.) originally targeted Pastor's seat instead of the one she currently holds. Others mentioned as possible contenders include Laura Pastor, the congressman's daughter, who was elected to a Phoenix city council seat last November. Former Phoenix mayor Phil Gordon; Mary Rose Wilcox, a long-time Maricopa County supervisor; Chad Campbell, a Democratic minority leader in the State House; Anna Tovar, the Senate Democratic leader; and Catherine Miranda.

Pastor was the first Latino congressman from Arizona and is a senior member of the House Appropriations Committee. He once helped secure federal funding for a light-rail system in Phoenix, but he also earned scrutiny from a Washington Post investigation for securing funding for a scholarship program headed by his daughter.

Pastor becomes the 33rd member of the House to announce plans to retire this year and 12th Democrat to do so. Twenty-one House Republicans have announced plans to step down.