Democratic Rep. Gabrielle Giffords’ announcement Sunday that she will resign from Congress elicited an outpouring of tributes from her colleagues and sets up a potentially competitive special election.

Arizona Gov. Jan Brewer (R) will have 72 hours to call special primary and general elections once the 8th district seat is declared vacant, which could happen by the end of this week.

In a statement Sunday, Giffords’ office stated she will attend Tuesday’s State of the Union address and finish her “Congress on Your Corner” event from a year ago, during which she was shot in the head and six others were killed. Giffords will submit her resignation to Speaker John Boehner (R-Ohio) later this week.

The special primary must occur 80 to 90 days following the vacancy, and the general must occur 50 to 60 days after the primary. All other standard processes remain the same, including that candidates must circulate petitions to get on the ballot.

The special will be run under the current district lines, which makes it highly competitive. Former Rep. Jim Kolbe (R) held the seat for 11 terms before Giffords won it in 2006.

Giffords’ announcement surprised some within Arizona Democratic circles. The hope that she could at least finish her term kept the identities of potential replacements well below the surface. On Sunday, many Democrats were not ready to begin publicly discussing candidates.

“We’ve got a very deep bench, and I’m confident we’ll be able to compete for that seat,” one party strategist said.

Officials identified a few officeholders with some ready-built operations who could run in the forthcoming special. They include state Sen. Linda Lopez of Tucson, who is close to Giffords; state Senate Minority Whip Paula Aboud; state Rep. Steve Farley; and Pima County Supervisor Ramon Valadez.

“We look forward to working with a Democratic candidate who fits this district and shares those values that Gabrielle holds dear to carry on her work,” Democratic Congressional Campaign Committee Chairman Steve Israel (N.Y.) said.

On the Republican side, state Sen. Frank Antenori has had an exploratory committee open for a few months, and a spokesman said Sunday that Antenori remains interested. Antenori lost in the 2006 GOP primary.

Another potential candidate is Dave Sitton, a college sports TV broadcaster, businessman and head coach of the University of Arizona rugby team. He has also formed an exploratory committee, but he did not return a message before press time.

The 8th district is currently 9,000 square miles and includes a 114-mile border with Mexico. It includes much of Tucson and the eastern edge of Pima County, as well as part of Santa Cruz County and all of Cochise County. President Barack Obama got 46 percent of the vote in the district in 2008.

Abby Livingston contributed to this report.