Rigas is holding down two jobs at the moment: He also was named late last month as the acting deputy director of management at the Office of Management and Budget.

Since taking charge, Rigas has put his stamp on OPM’s front office and is bringing George Nesterczuk on board as a senior adviser, according to two people familiar with the matter. He previously did organizational and HR consulting for government contractors and management consulting firms.

Nesterczuk had been Trump’s first choice to head up OPM but withdrew in August 2017 after criticism from federal employee unions who didn’t like the role he played in trying to enact a pay system based on performance at the Defense Department and raised questions about his work for the Ukranian government. He served two stints at OPM during both the Reagan and George W. Bush administrations and has also worked on Capitol Hill and at the Departments of Transportation and Defense.

Rigas has told colleagues that he questions the constitutionality of the 1883 Pendleton Act, which codifies using merit to pick government officials, and believes that all executive branch employees should be political appointees, according to a person who has discussed the matter with him.

The arrival of Rigas comes amid a push by McEntee and his allies to install other Trump loyalists across the executive branch.

McEntee is working in concert with Paul Dans, OPM’s new White House liaison and senior adviser, whose rapid efforts to consolidate his control over other agency appointees has irritated some officials.

Dans has also castigated other OPM officials for relying on career employees he suspects are Democrats, according to two people familiar with the interactions. He also has been asking how many policy jobs the government can shift from career officials to political appointees, a line of inquiry the people saw as an effort to install Trump loyalists in key posts.

Dans had no comment, but an OPM spokesperson said: "All employees in the executive branch have an obligation to carry out administration policy at the direction of the president, who is elected by the American people."

Other recent conversations inside the personnel office have raised further hackles. For instance, the Trump administration has had discussions on creating a new “schedule,” which regulates how agencies hire people, so they could make more jobs “excepted service” to make it easier to hire and fire people who are involved in policy jobs.

PPO is also trying to assert more control over who gets hired into political appointee jobs at some Cabinet departments, including the Departments of Education, Health and Human Services and a number of defense agencies, according to a former Trump administration official. Depending on the position, Cabinet agencies have typically had more latitude in choosing lower-ranking political hires.

But starting a few weeks ago, before some agencies fill a job, they now have to submit the opening to PPO to see if the White House has someone to place into the position. If they don’t have anyone, only then can the agency submit a name, the former official said. The result has left the personnel office “much stronger than they ever have been before,” this person said.

With greater authority has come a new round of clashes between various parts of the executive branches over personnel, with veteran officials in Cabinet agencies accusing McEntee of installing unqualified appointees in key posts.