It’s known as “burrowing in” — no, not what gophers and groundhogs do, but the quadrennial tradition practiced by that unique Washington animal: the federal worker.

As each administration winds down, some political appointees traditionally seek to continue their government service as career employees beyond the administration they served. Also known as “conversions,” the practice has attracted skepticism from government watchdogs and experts but has become known as something of a Washington ritual.

Now, Republican members of Congress are warning the Obama administration to follow the rules and ensure that any conversions are legitimate. In a letter to the U.S. Government Accountability Office, four Republicans ask that GAO study all conversions in federal agencies and commissions from June 1, 2009 through last month.

“The possibility that political appointees are ‘burrowing in’ – through favoritism in the selection process, effectively taking civil positions that would otherwise be open to the public and awarded based on merit – may affect the integrity of the merit-based federal workforce,” said the Nov. 20 letter, signed by Sen. Ron Johnson (R-Wis.), Sen. John Thune (R-S.D.), Rep. Jason Chaffetz (R-Utah) and Rep. Fred Upton (R-Mich.).

Although the letter only suggests that GAO “conduct periodic reviews in the future,” a Senate Republican aide made clear in a statement that the GOP will be watching during the Obama administration’s final year.

“Conversions can be legitimate, but there are also examples when political appointees have used their positions to gain unfair advantages,” said the aide, who spoke on condition of anonymity because he was not an authorized spokesman. “As the administration winds down, this GAO request should be a reminder to appointees  seeking out or receiving an offer of special treatment to stay in federal service beyond 2016: conversions will receive independent review to ensure that those who violate the rules are held accountable.”

A spokesman for the Office of Personnel Management, which oversees federal personnel practices, did not respond to a request for comment Friday afternoon. Under federal law, the government must follow a merit-based system in which all applicants for federal jobs are treated equally and discriminating for or against an applicant for political reasons is prohibited.

A GAO spokeswoman said the letter has been received but that the agency has not yet decided what to do.

Experts have said that burrowing can be especially attractive to younger political appointees in their 20s who may not have the experience to make the jump to a lucrative job on K Street or elsewhere once an administration ends.

If it conducts the investigation being requested, GAO would be following its own tradition of monitoring those who burrow.

In 2010, GAO reviewed 26 federal departments and agencies that converted 139 people from political to career positions from May 2005 through May 2009. While the majority of the conversions followed proper procedures, GAO said at least seven might have violated the merit-based system, including a Department of Veterans Affairs appointee who lacked the required experience and a Justice Department employee who received a career position despite unfavorable recommendations from government interviewers.

In a 2006 report, GAO found that at least 18 of 144 conversions did not follow proper procedures, such as agencies hiring appointees with limited qualifications and creating positions for specific individuals. In one case, GAO said, a confidential assistant to then-Health and Human Services Secretary Tommy G. Thompson beat out 52 other applicants for the newly reestablished position of policy coordinator in the secretary’s office. The job appeared to be tailor-made for the appointee, the GAO said.

The practice also extends back to the Clinton administration. A 2002 GAO report found 17 cases between October 1998 and April 2001 in which “the circumstances surrounding the appointment could, in our opinion, give the appearance that the appointees had received political favoritism or preferences.”