The expected departure of Rep. John McHugh (R-N.Y.) to the Obama administration has set off two races to replace him, one in his New York district, the other on his Washington-based Congressional committee.

McHugh had barely accepted the White House’s nomination for secretary of the Army on Tuesday before three members of the House Armed Services Committee began campaigning to replace him as the ranking member of the panel.

Reps. Roscoe Bartlett (R-Md.), who is next in line to McHugh in seniority on Armed Services; Howard McKeon (R-Calif.), who is ranking member on the Education and Labor Committee and ranks behind Bartlett on Armed Services; and Mac Thornberry (R-Texas), who is next in line behind McKeon, have all expressed interest in the job.

The House Republican Steering Committee, composed of 28 members of the House Republican Conference, is charged with the selection of the top committee positions.

Early Tuesday, Republican sources said Thornberry was the favorite to replace McHugh, but McKeon’s interest could change the equation.

McKeon, a longtime ally of Minority Leader John Boehner (Ohio), could have an advantage if he secures the Republican leader’s support. Boehner has five votes on the steering committee, more than any member of the panel. McKeon is also more senior than Thornberry on Armed Services.

However, one Republican source said Thornberry’s knowledge of defense issues could trump McKeon’s seniority.

A source close to McKeon said the California Republican scheduled a meeting with Boehner on Tuesday afternoon to discuss the position.

Bartlett and Thornberry both ran in 2008 to replace retired Rep. Duncan Hunter (R-Calif.) as the ranking member of Armed Services, but they were passed over by the steering committee in favor of McHugh.

A spokeswoman for Bartlett said that he was contacting colleagues to express his interest in the post. She declined to list whom Bartlett has spoken to, but said one of them was Boehner.

Bartlett said in a statement that he was confident Boehner and his colleagues would recognize his 17 years of service on the committee, as well as six and a half years as the top Republican on several subcommittees, including his current post on the Subcommittee on Air and Land Forces.

“In addition, my 20 years of experience in research and development for the military with 19 military patents and my advocacy for entrepreneurial innovation are well-known and respected,— he said.

Boehner and other Republicans expressed confidence on Tuesday that McHugh’s Congressional seat would remain in GOP hands.

“We will work hard to hold that seat into our column,— Boehner said.

He rejected the notion that the White House was deliberately trying to thin the ranks of Northeastern Republicans.

“I think they are looking for good people to put in these positions,— he said.

House Republican Conference Chairman Mike Pence (R-Ind.) said he isn’t concerned about his party losing another House seat held by a New England moderate. He dismissed “this talk about moderates feeling less welcome— in the Republican party.

“I’m going to sleep better at night knowing McHugh is secretary of the Army,— said Pence. The politics of finding another Republican to fill his vacant House seat “will sort themselves out.—

Rep. Fred Upton (R-Mich.) predicted that Republicans would easily hold onto McHugh’s seat.

McHugh’s district “is probably the safest seat in New York— for Republicans, said Upton. “I can’t imagine that we will lose that seat.—

McHugh’s absence sets up a highly competitive special election to replace him, a prospect that may fill both national parties with dread just months after a hard-fought special in an adjoining upstate district.

The 23rd district covers a wide swath of geography in upstate New York and is generally conservative territory. As of April 1, it had 167,000 registered Republicans, 121,000 registered Democrats, 76,000 unaffiliated voters and 20,000 registered members of the centrist Independence Party.

The Conservative Party had 5,600 enrolled voters, and another 2,500 were enrolled members of left-leaning third parties.

But even as McHugh was racking up another landslide last year, President Barack Obama took almost 53 percent of the vote in his district, a better showing than he had in the adjacent 20th district, another Republican stronghold on paper, where Democrat Scott Murphy prevailed in a special election earlier this year.

“This district is winnable with the right candidate, but it will be tough,— said Shripal Shah, a spokesman for the Democratic Congressional Campaign Committee. “Our focus is on working with local Democrats to begin the process of recruiting a strong candidate.—

Already names of potential candidates are circulating in both New York and Washington.

But while the 23rd is another potential pick-up opportunity for Democrats in the Empire State, where Republicans currently hold just three of 29 House seats, there is great risk for them as well. State Sen. Darrel Aubertine starts out as the leading Democratic contender, but he won his Senate seat in a special election last year, and his seat is in danger of flipping to the GOP if he leaves.

Democrats currently hold a tenuous 32-30 edge in the state Senate, and if Aubertine were elected to Congress and his seat fell into the Republican column, control of the state Senate would be evenly split, with no lieutenant governor in office to break tie votes.

Another potential contender is New York Democratic Chairwoman June O’Neill, a veteran of state government who lives in St. Lawrence County. Because the county party chairmen in the Congressional district would select the special election nominee — there is no primary — O’Neill would have a strong chance of winning the nod if she decided to run.

Other potential Democratic candidates include John Rhodes, a wealthy businessman who contemplated challenging McHugh in 2008, and St. Lawrence County District Attorney Nicole Duvé. Attorney Michael Oot, McHugh’s challenger last year, may also want to run again.

“There’s some talent up there,— said an Albany-based Democratic operative.

“The Democrats have some issues going on in the state that could spill over to the special election. But we can take comfort knowing Republicans have it worse.—

Nevertheless, the Republicans also appear to have a strong bench in the upstate district. Robert Taub, who has been McHugh’s chief of staff for nine years and is an upstate native, may try to run.

Other possible GOP contenders include: state Assemblywoman Dede Scozzafava; Franklin County District Attorney Derek Champagne; Essex County District Attorney Julie Garcia; Assemblyman Will Barclay; Assemblywoman Janet Duprey; Terry Gach, a vice president at the Trudeau Institute, a biomedical research facility in Saranac Lake; Michael Joyce, CEO of Hargrave Custom Yachts; and former state Sen. Jim Wright.

Both Garcia and Champagne are up for re-election this year.

The timetable for a special election depends largely on McHugh’s confirmation.

“Then we go to a sudden death penalty kick,— said Brendan Quinn, a former executive director of the New York GOP.

Jennifer Bendery contributed to this report.