The announcement that 10-term Congressman Doc Hastings will retire from the U.S. House of Representatives at the end of this year has opened up what will be one of the most watched races in the state come November.

Even though many Central Washington Republicans were taken by surprise with Thursday’s news, it took no time for political insiders to begin speculating on social media who the favorite might be if they choose to run for the 4th Congressional District, one of the most conservative districts in the country.

Hastings also weighed in on the question in an interview with the Yakima Herald-Republic, saying he has no doubt the district’s next congressman will be a conservative.

“Whomever it is that is elected will obviously have much the same philosophy as I have had if the past is prologue to the future,” Hastings said.

Late in 2013, Ephrata resident and self-described “constitutional activist” Gavin Seim announced he would be running for Hastings’ seat this year, but that was before other Republican hopefuls knew the congressman would be retiring. On Thursday, the state Democratic Party took to Twitter promising Democrats would challenge for the seat as well, and the 4th District Democrats put out an email soliciting interest from potential candidates.

Hastings said he has no idea who the all the candidates will be, but he hasn’t ruled out endorsing someone once the race is in motion.

“I don’t know what the field is yet, but I’ll certainly leave that option open,” he said.

Here are some names to keep an eye on:

• State Sen. Janéa Holmquist Newbry, R-Moses Lake: She was first elected to the state House of Representatives in 2000, and at age 31 in 2006 became the youngest woman ever elected to the state Senate. Holmquist Newbry currently serves as chairwoman of the Senate Commerce and Labor Committee, a position that has made her the face of Senate Republican efforts to reform state pensions, worker’s comp and prevailing wage requirements for government jobs.

Holmquist Newbry made waves earlier this week when she announced her displeasure with the Senate Majority Coalition Caucus’ support of a bill that makes undocumented residents eligible for state financial aid for college. Her Senate seat is also up for election this year.

• Former state Department of Agriculture director Dan Newhouse: He served in the state House of Representatives as a Republican from 2003 to 2009 before being named by Democratic Gov. Christine Gregoire to lead the state Department of Agriculture. In 2013, it was announced the Sunnyside farmer would not be retained by newly elected Gov. Jay Inslee, but Newhouse has remained active publicly, most notably for his opposition to last year’s state initiative to label genetically modified foods.

The Newhouse name is well-known in state politics. His late father, Irving Newhouse, served in the Legislature for 34 years.

• Benton County Commissioner Jerome Delvin: Those in Yakima may not be familiar with him, but Delvin is a well-known commodity in the Tri-Cities area, which may have greater sway over the district as a whole. Delvin served in the state House of Representatives from 1994 to 2004 before being appointed to the Senate and serving there until his election to the Benton County Commission in 2012.

Delvin worked for 28 years as a bomb technician and drug education officer for the Richland Police Department before retiring in 2007.

• State Sen. Curtis King, R-Yakima: First elected in 2007 to finish out the remainder of retiring Sen. Alex Deccio’s term, King rose through the ranks to become co-chairman last year of the Senate Transportation Committee. Over the last year, King has traveled the state promoting Republican proposals for reform to the state transportation system and has been in the middle of negotiations between both houses and the Governor’s Office over a transportation funding package.

• State Rep. Matt Manweller, R-Ellensburg: An up-and-comer in state politics who immediately dove into some of the causes most important to conservatives following his election in 2012, Manweller has been rumored to aspire to a higher office even before he declared his candidacy for the Legislature.

The only caveat is that Manweller, a professor at Central Washington University, no longer resides in the district after the state Redistricting Commission removed Kittitas County from the 4th District in 2011, but part of his legislative district still overlaps that area and the U.S. Constitution doesn’t necessarily prevent him from running.

Other potential candidates include State Sen. Sharon Brown, R-Kennewick, state Rep. Brad Klippert, R-Kennewick, state Rep. Charles Ross, R-Naches, and former NFL tight end and Franklin County resident Clint Didier, who ran unsuccessfully for public lands commissioner in 2012 and the U.S. Senate in 2010.

Candidate filing week is May 12-16. The state primary is Aug. 5.