Washington (CNN) When the Obama administration offered Thea Lay a chance to serve as one of the nation's top immigration judges pending a successful background check, she eagerly accepted.

But the Trump administration withdrew her offer this year with little explanation after months of silence -- and she suspects it's because of her political ideology.

Lay's case is one of several being questioned by House Democrats, who have accused the Justice Department of political bias in hiring judges to serve on the nation's immigration courts -- which would be against the law. And the suspicion of politically based hiring, even if unfounded, belies the greater criticism of Attorney General Jeff Sessions' broader efforts to speed up the immigration courts and use his authority as attorney general to single-handedly interpret immigration law.

Lay has spent much of her 25-year career working on the exact type of asylum law Sessions recently reinterpreted by rolling back protections for domestic violence victims, and she worries that she was perceived as having an ideology that would not be welcome on the Board of Immigration Appeals.

The Justice Department forcefully denies that political ideology has been a factor in any of its hiring of immigration judges, including the decision on Lay, citing federal laws which say it cannot be. They say Lay declined a temporary appointment to the position and cite that and a subsequent reevaluation of the salary for the position as the reason for her rejection.

But the questions about whether there was a quiet move away from candidates who were perceived as too pro-immigrant is an illustration of the unique position the attorney general holds, as the political appointee who hires, manages and can single-handedly overrule each of the nation's immigration judges.

Sessions has rolled out a number of policies designed to accelerate decision-making by judges, and has taken advantage of his unique authority to overrule Board of Immigration Appeals precedent on interpreting the law and set his own interpretations.

At the lower court level, immigration judges decide whether an immigrant can legally stay in the US or must be deported, but the Board of Immigration Appeals serves as the appellate body, with the authority to set precedent in interpreting immigration law for all immigration judges to follow.

Unlike federal judge positions, which are nominated by the President but must be confirmed by the Senate, immigration judges are hired directly by the attorney general and are structured not as independent arbiters, but as employees of the Justice Department. Because of that setup, they are thus subject to the same rules governing other career federal employees -- which prohibit administrations from picking and choosing based on political ideology. But the immigration judges' union has also complained that it gives a political appointee too much authority over their courts -- and even the appearance of political influence jeopardizes the neutrality of the system.

Politically motivated hiring is illegal, and past administrations have been reprimanded after investigations that found evidence of it. The IG completed an extensive investigation into political hiring at the department, including immigration judges, in 2008, finding that officials under the Bush administration had engaged in rampant political hiring for what should be career positions. Another investigation found similar problems with political hiring at the department's Civil Rights division.

Lay declined to be interviewed for this report but authorized her attorney, Zachary Henige, to speak on her behalf. She has filed a complaint with the Office of Special Counsel, a federal investigative agency that enforces government personnel laws, and with the Justice Department's inspector general regarding her withdrawn offer.

Lay has spent her career in the government working on complex immigration law and issues regarding asylum seekers and refugees. She started in the former Immigration and Naturalization Services in the 1990s and now works for US Citizenship and Immigration Services. As part of that position, Lay holds a high-level government clearance which was renewed last fall.

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Democrats say part of a pattern

Democrats in Congress say Lay's situation is not unique. In a letter to the Justice Department , House Democrats raised concerns about multiple immigration judges who were approved for positions under the Obama administration, only to have the offer withdrawn or languish for months under the Trump administration without resolution.

CNN spoke with four other individuals who had offers for immigration judge positions: two of whom had the offer withdrawn and two who had yet to hear about their application. All declined to use their name in this report, citing concerns about their current positions and the sensitivity of the issue.

After the Democrats' letter, the Justice Department approved six pending applications -- including the ones CNN had spoken with as they were waiting to hear about their case -- according to a response sent to Democrats by the Justice Department. All of the candidates CNN spoke with had been approved for positions under the previous administration, which means they completed the lengthy application, sat through two separate panel interviews, and met all the qualifications. As the positions are by law non-ideological, qualified candidates should transcend administration. All that was left was a background investigation.

In Lay's case, the agency did not cite anything in her background check as the problem, but said she had been offered -- and declined -- a temporary appointment to start the position immediately while her background check was conducted. The department then reviewed the "classification" and "appropriate salary level" for the position, and "the candidate's lack of demonstrated interest and commitment in filling the position during a time of need, coupled with the position and salary review, resulted in the withdrawal of the offer," Assistant Attorney General Stephen Boyd said in a letter to the House Democrats who had raised the issue.

Though the letter did not use Lay's name, CNN was able to identify the justification for her withdrawn offer in the letter based on information provided by her attorney. The Justice Department said the remaining rejections were based on information found in the background investigation or pre-employment process.

Lay's attorney, Henige, rejects that explanation, saying that Lay had a conversation with the previous director of the immigration courts division and was plainly told that turning down the temporary appointment would not reflect negatively on her application. To take the temporary position, Lay would have had to sign a waiver that would have given up her decades-long government position without a guarantee of full employment in the future. She was in touch with the previous director until he left the position last spring, when he told her that she would likely receive her appointment as soon as the background check cleared, and then heard nothing until February of this year, when her withdrawal notice came, Henige said.

That letter, which said "the needs of the agency ha(d) evolved," came within a week of the Justice Department publicly saying its need for judges on the Board of Immigration appeals was so great, it was adding four new positions it would begin hiring for.

The Justice Department denied there was any political motive in Lay's case.

"The Department of Justice does not discriminate potential hires on the basis of political affiliation," a DOJ spokesperson told CNN. "The detailed letter to certain members of Congress addressing why certain immigration court candidates are no longer under consideration directly and fully refutes the accusations that have been made. Our confidence in the integrity of the immigration judge hiring remains high."

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But Lay's lawyer doesn't buy the explanation.

"The agency now appears to have shifted its position by claiming Ms. Lay must have lost interest in the position and that salary considerations were involved in the withdrawal," Henige said. "But (the Executive Office for Immigration Review's) offer letter was merely contingent on a background investigation. And EOIR never contacted Ms. Lay about her continued interest or about any needed salary adjustments. Without a legitimate nondiscriminatory basis for revoking her job offer, it appears that EOIR's bases for failing to follow through and place Ms. Lay and possibly other individuals into their offered positions is political or otherwise illegal."

House Democrats also were not satisfied by the Justice Department's letter, saying the agency still had not produced the documents they originally sought in their investigation.

"The Department of Justice's response to our inquiry provides further evidence—in additional examples of delayed appointments—that the Trump Administration may have delayed multiple immigration judge appointments for political reasons," said Democratic Reps. Elijah Cummings and Lloyd Doggett in a statement . "Only after we made this issue public and requested an Inspector General review did the department finally end some of these delays and appoint six of those judges."

Like the other individuals who suspected political motivations in their rejections, Lay believes her resume and application would instantly come across as pro-immigrant -- fair or not. She has spent decades working on asylum policy, especially the types of issues Sessions recently rolled back with a decision to not consider victims of domestic violence or gang-related crime eligible for asylum. Inside the government, USCIS is perceived as the most pro-immigrant of the immigration agencies, being the agency that bestows visas and citizenship on immigrants.

Her recommendations also came from academics and former Democratic political appointees. One of her recommenders, Stephen Legomsky, says the department would have been making a mistake if that was their calculation.

"As chief counsel of USCIS, I was Thea's direct supervisor," Legomsky, now a Washington University School of Law professor, told CNN. "This will sound like an exaggeration, but honestly, Thea is one of the most brilliant, knowledgeable, experienced immigration attorneys, one of the most fair-minded, collegial attorneys I've known in any setting. She's really off the charts."

Executive Office of Immigration Review Director James McHenry has repeatedly stated that the hiring is based on merit-systems principles, which explicitly would not allow any discrimination based on political affiliation.

"All of our hiring is conducted according to merit-systems principles," McHenry testified in a House hearing last year. "We don't require any information regarding any organizations or anything like that that individuals belong to. We evaluate them based on resume, interviews, writing samples, things like that. ... We don't consider things like race, religion, political opinion, things like that."

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Need for more judges

The immigration judge hiring process has traditionally taken upwards of two years, between the lengthy application process, interviews and background checks.

Sessions has made hiring immigration judges -- and overhauling the immigration courts more broadly -- a top priority under his administration, with the consistently burgeoning backlog of cases, now over 600,000, slowing down decisions on whether immigrants are allowed to stay in the country for years.

One of Sessions' early actions was to streamline the hiring process, the Justice Department says by putting deadlines on various steps in the process. The process has been condensed by more than half from more than 700 days to 10 months to a year, McHenry said recently. Sessions has also pushed for more congressional funding for judge positions and has introduced a number of controversial measures to speed up the actual case adjudication process.

The backlog means that all of the immigration judges this administration has hired were actually selected by the previous administration, already in the pipeline when Sessions took over.

Roughly three out of four immigration judges appointed by this administration have prosecutorial experience and many worked for Immigration and Customs Enforcement, the entity that arrests many of the immigrants that end up before the judges. CNN has analyzed all of the announcements for immigration judges since inauguration, including an analysis of their biographies. The first third, roughly, had their appointments finalized under the previous administration, with the remaining two-thirds getting final approval under Sessions, but the rate of prosecution and ICE experience was fairly consistent among both groups.

Of the roughly 25% of appointees who did not have prosecution experience, most had either private practice experience or some other government experience, including work as a judge. Only a small handful had experience with nonprofits that typically work on the side of immigrants.

Legomsky, a critic of Sessions, worried that in the context of other actions Sessions has taken to influence the immigration courts, that Lay's withdrawn offer is a red flag.

"I do think this is really part and parcel of a strategy to manipulate the legal process, and that's why it concerns me as much as it does," Legomsky said.

CORRECTION: This story has been updated to reflect that Democratic Reps. Elijah Cummings and Lloyd Doggett issued a statement to the Department of Justice.