Michael Shank said Monday that he is running out of time to secure an engine for his Indianapolis 500 entry.

The team owner announced last week that he had filed an entry for Jay Howard, and has a sponsor in place for the May 27 race. But he doesn't have an engine, and if neither Chevrolet or Honda agree in the next day or so to lease him one, Shank said he'll have to pull the plug on the entry.

"It doesn't look like we are going to be able to work anything out as we sit here today," Shank said in a phone interview. "We are up against the calendar, just in terms of being able to run competitively. It's been two weeks, two weeks of just not being able to get anything done, and it really, really bums me out on so many levels."

If Shank withdraws his entry, it could drop the Indy 500 below the traditional 33 cars for a full field.

Newman/Haas Racing told The Associated Press last week it has withdrawn its entry, which dropped the official entries to 34.

There were 34 official entrants on the initial list, and Shank made 35. But the official entry list only had 30 announced driver-team combinations when it was released by Indianapolis Motor Speedway.

Rahal Letterman Lanigan has since announced Michel Jourdain Jr. for its entry. Ed Carpenter Racing and Sam Schmidt Motorsports are also on the official entry list, and neither has announced its drivers. It's possible one or both of those entries won't come to fruition.

The race has had a full field every year since 1947, when it had 30 cars. In 1979 and 1997, the field was expanded to 35 cars.

Shank, who fielded teams that finished first and third in this year's Rolex 24 Hours of Daytona race, has had difficulty getting his IndyCar team off the ground since its launch in October. NASCAR driver AJ Allmendinger is a part-owner in the IndyCar effort.

The initial plan was to run veteran Paul Tracy in a farewell tour or sorts for the full IndyCar schedule, but the current engine situation in IndyCar, coupled with difficulty in finding full season sponsorship, prevented Shank from getting the team off the ground.

Now, even moving forward on a one-off Indy 500 effort is proving problematic. Shank said he is only interested in partnering with Chevrolet or Honda, and doesn't want a Lotus engine just for the sake of running the race.

"I've got nothing against the people at Lotus, but this is a huge risk for me and my life and my team, and I am not willing to do it with zero hope," Shank said. "And there's no hope of getting a top 10 with a Lotus."

Shank was initially listed as a Lotus team when he announced the team in October. But the manufacturer was never able to get him an engine, and last week agreed to release two teams from its contracts. It now has three cars signed on for engines this season.

Chevrolet, meanwhile, has 11 cars and Honda has 10. Both have some room to provide additional engines for the Indianapolis 500, where the field expands from 26 to the traditional 33 cars.

Shank said he doesn't have time to wait for the manufacturers to fill their lineups.

"I've left messages with everyone," Shank said. "We had a deadline set up for last night, for us internally, just to physically get the work done. If you are an established team, maybe you can wait this out because you have your systems in place. But me, we're starting from scratch.

"And the sponsorship? That's not going to last forever. If something doesn't happen today or tomorrow, we are eventually going to lose that, too."

Jim Campbell, U.S. vice president for Chevrolet performance vehicles and motorsports, told The Associated Press at Saturday night's NASCAR race that the manufacturer is near capacity for its Indy 500 effort. Should some engines that are presently spoken for become available, Campbell said he'd work with the existing Chevrolet teams to meet their needs before offering engines elsewhere.

Campbell was then at Homestead on Sunday for the Grand-Am race, and Shank said the two talked briefly about the Indy 500. Shank also said he's hoping IndyCar CEO Randy Bernard will work with Chevrolet and Honda to help small teams get engines.

Both Chevrolet and Honda are expected to help pick up the slack for the two teams that left Lotus last week. Bryan Herta Autosport is expected to partner with Honda, while Dreyer & Reinbold Racing are expected to get Chevrolet engines.

But Campbell said no deals with BHA and DRR were completed, and the discussions would likely heat up this week.

"If in a week or so engines become available and go elsewhere, that is really, really going to disappoint me," Shank said. "That would be a true slap to us. I asked IndyCar to just guarantee we'll get an engine, just guarantee will get something from one or the other, and they never responded."