WASHINGTON — The Air Force’s B-21 Raider program could stagnate under a year-long continuing resolution, as the lower funding stream would slow development and possibly even delivery of the new bomber, the service’s number-two civilian warned Thursday.

Congress is rushing to avoid a government shutdown, which will occur unless lawmakers pass a short-term funding stopgap by Friday. But the Air Force is getting increasingly worried that even the best case scenario — another CR — could curb key modernization efforts like the B-21, its Undersecretary Matt Donovan said.

“A long-term CR will limit execution of the engineering, manufacturing and development phase, the EMD phase, of the B-21,” he said at an Air Force Association event. “We would be limited to the FY17 funding level, which is far below the FY18 budget request. This will have the effect of postponing delivery of the critical strategic capability to the joint warfighter.”

The Air Force allotted $2 billion in its unclassified FY18 budget request for continued EMD activities, up from $1.3 billion the previous year. While the B-21 program currently remains on track, Donovan stated the program will be negatively affected as early as April if the Defense Department remains entangled in a CR.

Northrop Grumman won the B-21 contract in 2015 after a protracted battle with a Boeing-Lockheed Martin team. The Air Force currently intends to buy at least 100 B-21s, with the fielding of the first bombers planned for the mid-2020s.

Asked for details on how long initial operational capability could be deferred if budget instability continues, Donovan refused to say much more than that.

“If we’re not able to ramp up on our schedule for the acquisition program baseline, of course it’s going to have an impact on the other end. You can’t make up that time,” he said.

Along with impacts to the service’s modernization priorities, a yearlong CR would also have a dramatic impact on its attempts to boost readiness. Instead of an end strength of 325,000 active duty airmen, the service would be limited to 321,000 airmen.

It would also shave $2.7 billion from its operations and maintenance accounts, which pay for depot maintenance and flying hours. Faced with less money than planned, the service would likely cut training, “especially for the high-end fight,” Donovan said.

Even a late budget deal like the once reached last May could have unforeseen repercussions.

“The problem [with the FY17 deal] is that while it plugged some programmatic gaps, it became so late in the year, that we ended up having a problem spending the O&M one-year money,” he said.

White House press secretary Sarah Sanders has indicated President Donald Trump’s support for a short-term stopgap. One option is a Republican-backed proposal set for a vote this afternoon, which would fund the government until Feb. 16. If that happens, the Defense Department’s FY19 budget request could hit the streets before Congress passes a budget for the prior year.

Donovan declined to comment on the specifics of the Air Force’s upcoming request, but said the administration developed the National Security Strategy, National Defense Strategy and the FY19 budget in parallel, and that all focus on how the U.S. military can regain its edge against Russia and China.

One program that is sure to get more money: The B-21 Raider.

“I’m not going to tell you what the number is, but you can expect that it is going to increase as we build up this program,” Donovan said.