Mueller Seats Grand Jury in Russia Probe, Wall Street Journal ReportsSpecial Counsel Robert Mueller has seated a grand jury, The Wall Street Journal reports, meaning his probe into Russian interference in the 2016 presidential election is growing. Investigators and prosecutors use grand juries to examine evidence, grill witnesses and subpoena documents to determine if a crime has been committed. It is a serious step in any investigation. The Journal says the panel began its work in recent weeks and will likely continue for months. Mueller and his team of lawyers are looking into possible collusion between Russia and the Trump presidential campaign. Reuters reports the grand jury has already issued subpoenas in connection with the June 2016 meeting a Russian lawyer and others held with Donald Trump Jr. and other top campaign officials. Reports indicate the younger Trump jumped at the idea of a meeting when the the lawyer told him, through an intermediary, that she had incriminating evidence against Democratic presidential candidate Hillary Clinton. President Donald Trump has cast doubt on whether the Russians tried to interfere in the election, despite intelligence reports that the Kremlin sought to manipulate the election in Trump's favor. Trump has consistently denied any collusion. He called Mueller's probe "a witch hunt" and reports around Washington have said the president may try to fire him. Subpoena power Now that a grand jury has reportedly been seated, it could seek to subpoena Trump family financial records. The president has warned Mueller to stay away from his finances. Mueller's office has not commented on the Wall Street Journal report. Trump special counsel Ty Cobb said that he is unaware of a grand jury probe but says "the White House favors anything that accelerates the conclusion of his work fairly ... the White House is committed to fully cooperating with Mr. Mueller." Mueller, a former FBI director took over the Russia probe after Trump fired his own FBI director James Comey in May when Comey apparently refused Trump's request to back down from the investigation. Bill to Protect Special Counsel Also Thursday, two U.S. senators introduced a bill to make it hard to fire a special counsel. The proposal by Democrat Chris Coons and Republican Thom Tillis would put into law that a president can only fire the investigator for misconduct, conflict of interest, severe illness or other good cause. A three-judge panel would determine if the firing was justified. The law is apparently an effort to protect Mueller from any attempt that Trump would fire him. But some analysts say if the president wants to fire Mueller, the proposed legislation may prompt him to do it before the Senate has a chance to vote on the new law. The bill would apply retroactively to May 17, 2017 — the day Mueller was appointed by Deputy Attorney General Rod Rosenstein to investigate allegations of Russian meddling in the 2016 election and possible ties between Russia and Trump's presidential campaign.\n\n"This is something that lives long beyond this'' situation involving Mueller, Tillis told reporters. "And I think it's also something that begins to re-establish the reputation for independence in the Department of Justice.''\n\nTillis was among many GOP senators who defended Attorney General Jeff Sessions after Trump criticized him for recusing himself from the Justice Department's investigation into suspected Russian interference in the election. Trump has threatened to fire Sessions, a former Alabama senator. Some information for this report from AP.