(Adds details; byline)
By David Schwartz
PHOENIX, Jan 27 (Reuters) - Arizona Governor Jan Brewer on Friday ordered a special general election to be held on June 12 to fill a congressional seat vacated by Tucson Democrat Gabrielle Giffords, who resigned to focus on recovering from a gunshot wound to the head.
The Republican governor also set an April 17 primary to choose the candidates who will vie to replace Giffords in what has proved to be a highly competitive district in southern Arizona.
Giffords left office on Wednesday, cutting short her third term representing Arizona's 8th congressional district as she continues to recover from a gunshot wound that left her with faltering speech and physical impairments.
She was shot at close range by a gunman who opened fire at a meet-and-greet for constituents outside a Tucson supermarket on Jan. 8, 2011. Six people were killed and 12 others were wounded.
Giffords, in a resignation letter read aloud on the floor of the U.S. House of Representatives by close friend and fellow Democrat Deborah Wasserman-Schultz, said her district "deserves to elect a U.S. representative who can give 100 percent to the job."
Giffords won re-election by a slim 4,000 votes during the last election in 2010, brightening Republican hopes that the seat may again be within their gasp. Before Giffords, it was held by Republican Jim Kolbe for 22 years.
Republicans now hold a voter registration advantage of 6 percentage points over Democrats in the district.
District voters will go to the polls twice more this year, with the regular election primary scheduled for Aug. 28 and the general election on Nov. 6. The regular election will be held under redrawn congressional lines that all but make it a dead-even split between Republicans and Democrats.
Possible Republican candidates for Giffords' seat include state Senator Frank Antenori, who on Friday became the first to announce his bid in both elections, as well as Dave Sitton, a University of Arizona sports broadcaster, and Jesse Kelly, who lost to Giffords in 2010 and had strong Tea Party backing.
Among Democrats believed to be considering at run are Steve Farley, a state representative and assistant majority leader, state Senator Paula Aboud and state Representative Matt Heinz.
Also mentioned as a possible candidate has been Giffords' husband Mark Kelly, a retired astronaut. But Kelly quashed speculation that he might run for her seat during a video-conference call with Arizona reporters on Wednesday.
He also said there was a "pretty good chance" that Giffords would endorse a person to replace her, a move that political observers say promises to provide a big boost for any candidate.
The accused gunman in last year's shooting spree, Jared Loughner, 23, has pleaded not guilty to multiple charges stemming from the rampage, include first-degree murder and the attempted assassination of Giffords. He was declared mentally incompetent to stand trial last May. (Reporting by David Schwartz; Writing by Steve Gorman; Editing by Paul Thomasch and Cynthia Johnston)