(Reuters) - U.S. National Security Adviser H.R. McMaster is most likely the next official to leave the Trump administration, following a string of firings and resignations, according to an online betting website said which put the odds against him staying at 3/2.

Slideshow ( 3 images )

President Donald Trump’s record-setting personnel turnover inspired Costa Rica-based BetDSI to begin taking bets on White House departures and it said the chances for any particular staff member remaining employed in the White House were not high.

"Due to the ongoing turnover we’ve seen thus far in the Trump Administration, no member on this list can feel particularly safe in their position," BetDSI said in a statement on the 24 Trump officials it gave odds for. bit.ly/2HIj68f

Turnover among White House senior staff during Trump’s first year was at least twice as high as that of any of the five past presidencies, according to Brookings Institute research.

After firing U.S. Secretary of State Rex Tillerson on Tuesday, the president has been talking to confidants about replacing McMaster and Veterans Affairs Secretary David Shulkin, sources familiar with the conversations told Reuters this week.

Indeed, the likelihood Shulkin will be removed within days were so high that BetDSI said it did not include him on its odds list.

Most likely to exit, after McMaster, were Attorney General Jeff Sessions and Press Secretary Sarah Sanders, with odds of 7/4 and 6/1, respectively.

Among staff whose jobs appeared most secure were Vice President Mike Pence at 50/1 and Small Business Administration chief Linda McMahon with the same odds, according to BetDSI.

Such is the concern among White House employees about job security that Chief of Staff John Kelly on Friday assured Trump aides that no immediate personnel changes were in the works, Sanders told reporters on Friday.

(This version of the story states odds as fractions)