By Lawrence Hurley and Andrew Chung

WASHINGTON, May 12 (Reuters) - The U.S. Supreme Court on Tuesday hears arguments in a major showdown over presidential powers arising from President Donald Trump's attempts to prevent Democratic-led congressional committees and a New York City prosecutor from getting his financial records.

Three months after Trump avoided removal from office in a Senate impeachment trial, Trump's lawyers want the Supreme Court to endorse their expansive view of presidential powers that would severely limit the ability of Congress to conduct oversight of presidents and of prosecutors to investigate them.

The Supreme Court has a 5-4 majority including two justices appointed by Trump. He has won key victories at the high court including over his hardline immigration policies but lost a big case a year ago regarding the U.S. census when conservative Chief Justice John Roberts joined the court's four liberals.

In the three cases being argued on Tuesday, Trump has sought to prevent enforcement of subpoenas issued to his long-time accounting firm Mazars LLP and two banks, Deutsche Bank and Capital One, for financial records including tax returns. Lower courts in Washington and New York ruled against Trump in all three cases.

Trump, unlike other recent presidents, has declined to release his tax returns and other financial records that could shed light on his net worth and the activities of his family real-estate company, the Trump Organization.

Rulings are likely within weeks, with Trump seeking re-election on Nov. 3 amid the coronavirus pandemic. The cases will be heard in two separate arguments by teleconference, a format adopted during the pandemic.

The cases are among the most consequential in years on the parameters of presidential powers. The high court in some past landmark cases has ruled against presidents.

In 1997, it unanimously decided that sitting presidents could be sued for conduct outside of official duties, ruling against President Bill Clinton's bid to delay a sexual harassment lawsuit. In 1974, it unanimously ruled that President Richard Nixon must comply with a court's subpoena for tape recordings in the Watergate scandal.

Two of the Trump cases - to be heard together - concern his effort to block enforcement of subpoenas by House of Representatives committees seeking his financial records from Mazars and the two banks.

The House committees have said they are seeking the material as part of investigations into potential money laundering by banks and into whether Trump inflated and deflated certain assets on financial statements - as his former personal lawyer has said - in part to reduce his real estate taxes.

The other case concerns a subpoena issued to Mazars for similar information, including tax returns, as part of a grand jury investigation into Trump being conducted by the office of Manhattan District Attorney Cyrus Vance, a Democrat.

The New York criminal investigation was spurred by disclosures of hush-money payments by Trump to two women - pornographic film actress Stormy Daniels and former Playboy model Karen McDougal - who said they had past sexual relationships with him.

Trump's lawyers have argued that Congress had no authority to issue the subpoenas and that the House Democrats had no valid legislative reason for seeking the records.

In the New York case, Trump's lawyers argued that his records cannot be handed over because of his authority as president under the Constitution, contending he is immune from any criminal proceeding while in office. Even if Trump shot someone on New York's Fifth Avenue, prosecutors would be powerless to act while he was still in office, his lawyers argued before losing at a lower court.

(Reporting by Lawrence Hurley and Andrew Chung; Additional reporting by Jan Wolfe)