Special counsel Robert Mueller's Russia investigation will be under increasing pressure to adhere to Justice Department guidance aimed at making sure the department's work doesn't influence elections — guidance that was put in place by President Barack Obama's attorney general, Eric Holder.

The possibility that Mueller's work could affect the midterm election either way is an idea that has crossed the minds of Republicans and Democrats alike. President Trump worried Tuesday that Mueller’s team might be open to "meddling" with the election, and Sen. Chris Coons, D-Del., said Wednesday that it's "important" for Mueller to "avoid any major announcements" in the months ahead of the midterms.

"And I fully expect him to follow that practice," Coons told CNN.

Guidance that Holder put in place in 2012 is aimed at preventing those sorts of outcomes. It's not foolproof, as Mueller is still permitted to run his investigation as he sees fit.

But the guidance makes it clear that Mueller cannot try to time his next steps in order to influence the election.

“Simply put, politics must play no role in the decisions of federal investigators or prosecutors regarding any investigations or criminal charges. Law enforcement officers and prosecutors may never select the timing of investigative steps or criminal charges for the purpose of affecting any election, or for the purpose of giving an advantage or disadvantage to any candidate or political party,” reads the March 2012 memo from Holder.

A spokesman for Mueller declined to comment on whether his team is following the memo, but a Justice Department official told the Washington Examiner that the guidance is still in effect.

Experts on the subject made it clear that the memo does not mean Mueller must cease all work related to his investigation as the election gets closer. In Mueller’s investigation for example, the trial of former Trump campaign chairman Paul Manafort begins in Washington in September, meaning it could stretch into October, just as voters are considering their choices in November.

Sentencing for some people who plead guilty could also begin around election time. Mueller has brought dozens of criminal charges against more than 20 defendants.

Still, the Holder memo is aimed at making sure investigators do as little as possible to disrupt elections, and encourages discussion within the department on how to achieve this goal. For example, it tells Justice Department employees to reach out to the Public Integrity Section of the Criminal division “if you are faced with a question regarding the timing of charges or overt investigative steps near the time of a primary or general election.”

The 2012 Holder memo also says "more guidance" can be found in the Justice Department’s U.S. Attorney’s Manual. That manual puts limits on how prosecutors can act, and says they need to ensure decisions are not influenced by the target's race or other personal characteristics, "the attorney's own personal feelings" about the target, or "the possible affect of the decision on the attorney's own professional or personal circumstances."

Scott Fredericksen, a former federal prosecutor and independent counsel, told the Washington Examiner that he thinks Mueller will follow Justice Department policy and be mindful of his actions around the midterms.

“Mueller will abide by that policy, and that will be his guiding light. He has conducted his investigation completely consistent with all DOJ policy,” Fredericksen said. “That said, there is something of a looming conflict because it’s I think a priority for Mueller to complete this investigation as fast as possible, and at the end, or close to the end, he will either issue indictments and/or issue a report to [Deputy Attorney General] Rod Rosenstein to be sent to Congress.”

“Once he gets into that window, especially in October, I think he will be reluctant to issue a report or take an action that close to Nov. 3,” he said.

Rosenstein oversees Mueller’s investigation, and will receive a report from Mueller at the conclusion of his investigation. Rosenstein doesn’t have to disclose the report to Congress should Mueller find Trump did or did not commit wrongdoing, especially if decisions are revealed around election time, but there will likely be pressure for him to do so.

“Obviously I would suspect [Mueller] already has in his mind he does not want to time that anywhere close to the election. I would guess that in his mind, if he is going to take any action, sometime around Labor Day would be a deadline in his mind,” Fredericksen explained. But he noted there are “circumstances” that could arise to push it past Labor Day.

“One of those reasons could be negotiating the interview with Trump,” he said.

In the meantime, Trump continues to call the investigation a "witch hunt," and his team has made it clear it doesn't want to be hurt by late-breaking news just as people prepare to vote. Rudy Giuliani, the former New York City mayor who is now Trump’s attorney, told reporters Wednesday that Mueller should wrap up his investigation by September, implying that the mere existence of the investigation after that would be a form of meddling.

"If he doesn't file a report by Sept. 1, mid-September, he's clearly doing a Comey,” he said. That's a reference to former FBI Director James Comey, who drew criticism in the weeks leading up to the 2016 election for revealing that Democratic presidential nominee Hillary Clinton was once again being investigated by the bureau for a private email server.