The Pentagon said on Thursday that it was delaying the award of a hotly contested $10 billion contract for a new generation of computing services for the military until the secretary of defense, Mark T. Esper, could review the matter.

[Update: Microsoft wins Pentagon’s $10 billion JEDI contract, thwarting Amazon.]

The announcement came just a week after Mr. Esper’s confirmation and two weeks after President Trump said he would be looking “very seriously” at the contract process to move the military to a cloud-computing system. Mr. Trump said his concern was based on what he called “tremendous complaints” from competitors of Amazon Web Services, the division of the merchandising giant seen as the all-but-certain winner of the contract.

The development was evidence of how what began as a technological competition to remake the military’s aging, often incompatible computer systems now seems to have taken on a political and possibly personal element driven by Mr. Trump, who has frequently attacked Jeff Bezos, the founder of Amazon who also owns The Washington Post. When angered by the paper’s coverage, Mr. Trump often refers to it on Twitter as the “Amazon Washington Post.”

Experts on federal contracting say it is extremely rare for a president to intervene in a contract competition and improper to do it for political reasons.