Two attorneys working with clients involved in special counsel Robert Mueller's Russia probe who spoke to Politico said they believe Mueller could indict President Donald Trump for obstruction of justice, a historic first for a sitting president, possibly as soon as this Spring.

While neither attorney "claimed to have specific knowledge of Mueller's plans," both "based their opinions on their understanding of the law," and one of them "cited his interactions with the special counsel's team."

"If I were a betting man, I'd bet against the president," said one of the lawyers.

The second attorney, who represents a senior Trump official, believes Mueller could try to bring an indictment against Trump even if he anticipates legal and procedural challenges.

"It's entirely possible that Mueller may go that route on the theory that, as an open question, it should be for the courts to decide," the attorney said. "Even if the indictment is dismissed, it puts maximum pressure on Congress to treat this with the independence and intellectual honesty that it will never, ever get."

Legal scholars have opined that a case against the president would likely move to the Supreme Court because there is no legal precedent for an indictment of a president. Two Justice Department legal opinions––one in 1973, the other in 2000––say it's "not a viable option." As Politico reports:

The 2000 opinion concluded that the indictment or criminal prosecution of a sitting president "would unconstitutionally undermine the capacity of the executive branch to perform its constitutionally assigned functions."

The memo was written by an assistant attorney general nearly two years after the House impeached President Bill Clinton for lying under oath and obstructing justice about his affair with White House intern Monica Lewinsky.

Independent counsel Kenneth Starr never tried to indict Clinton. But Starr, who filed a damning report to Congress in 1998, considered the option — and even tasked his lawyers with preparing draft indictments, as well as a legal opinion asserting his power to charge Clinton.

As for the 1973 memo:

The 1973 Justice Department memo was used to shield President Richard Nixon from a possible indictment by Watergate prosecutors, who believed they had the power to bring one. That debate was unresolved after the special prosecutor decided to share his work with the House Judiciary Committee, which was preparing to launch impeachment proceedings against Nixon.

According to Kenneth Starr's legal adviser, Ronald Rotunda, Mueller cannot indict Trump because Starr's powers were defined by an independent counsel statute that expired in 1999. As such, Mueller has the powers of a U.S. attorney, and would be bound by all Justice Department "rules, regulations, procedures, practices and policies," including both the 1973 and 2000 DOJ memos.

Republicans have warned that an indictment against a sitting president would spark a constitutional crisis, and signs that Mueller is closing in have persisted for months.

In October, Mueller's team charged former Trump campaign chairman Paul Manafort and his longtime business partner Rick Gates with 12 counts of "conspiracy against the United States, conspiracy to launder money, unregistered agent of a foreign principal, false and misleading FARA statements, false statements, and seven counts of failure to file reports of foreign bank and financial accounts."

Shortly afterward, Trump's former national security adviser, Michael Flynn, pled guilty to lying about conversations he'd had with Sergey Kislyak, the former Russian ambassador. Mueller's team charged Flynn with "willfully and knowingly" making "false, fictitious and fraudulent statements" regarding those conversations. Flynn's plea indicates what outlets had reported for some time: That he is cooperating with the special counsel's investigation.