Washington — A report revealing that Justice Samuel Alito took a luxury fishing trip with a wealthy Republican donor with ties to cases before the Supreme Court has sparked new criticisms of the justices' adherence to their ethical obligations.

The Supreme Court was already under scrutiny for justices' compliance with ethical standards due to a series of revelations about Justice Clarence Thomas's decades-long relationship with GOP megadonor Harlan Crow. 

But according to a report from ProPublica published late Tuesday, Thomas is not the only justice who has accepted luxury trips from prominent Republican donors. The investigative news outlet reported that in July 2008, Alito flew to Alaska aboard a private jet for a vacation at the King Salmon Lodge, a luxury fishing resort that charged more than $1,000 per day.

The jet was provided by Paul Singer, a hedge fund billionaire, and Alito's accommodations at the lodge were covered by Robin Arkley II, who owns a mortgage company and donates to conservative causes, the report said. 

Singer's hedge fund and related entities had asked the Supreme Court to intervene in disputes it was involved in. In 2014, the high court heard a long-running legal fight between an affiliate of his fund and Argentina. The Supreme Court ruled for Singer in a 7-1 decision, with Alito in the majority.

Neither the lodging nor travel aboard Singer's jet were included on Alito's annual financial disclosures.

"There is something rotten going on in the Supreme Court of the United States of America," Sen. Dick Durbin, who chairs the Senate Judiciary Committee, told reporters on Wednesday. "There is one person who can resolve it and do it this morning, and that's Chief Justice John Roberts. If he steps up and decides that we'll finally have a code of ethics on the Supreme Court, it could be a new day for the court."

Durbin called Alito's defense of his trip — aired in a preemptive opinion piece published by the Wall Street Journal before ProPublica published its article — "laughable."

"That is an incredible response to the challenge that's been made," he said.

In his Wall Street Journal response, Alito argued he had no obligation to recuse himself from the cases involving Singer's businesses and said that stepping aside "would not have been required or appropriate." The justice, who has served on the high court since 2006, said he has spoken to Singer "on no more than a handful of occasions," and they never discussed his business activity or issues before the Supreme Court. He also said he did not know of Singer's ties to the parties involved in the cases cited in ProPublica's article.

Regarding the trip aboard Singer's private jet, Alito said he sat in a seat that would otherwise have remained vacant on the flight to Alaska.

Alito also refuted the suggestion that the travel and lodging should have been reported on disclosure forms, which allow exceptions for personal hospitality "on property or facilities owned by [a] person." Referencing several dictionary definitions, Alito said the jet constituted a "facility," and the justices "commonly interpreted" hospitality to include accommodations and transportation for social events that did not have to be reported as gifts.

Alito also addressed the characterization of his trip as one of luxury, writing that he stayed in a "modest one-room unit" for three nights at the King Salmon Lodge, a "comfortable but rustic facility."

The Supreme Court was already under heightened focus from Senate Democrats before the revelations about Alito's trip. The Judiciary panel held a hearing, to which Chief Justice John Roberts was invited, examining the ethical standards the justices adhere to last month. The chief justice declined to attend the proceeding but shared a Statement of Ethics Principles and Practices signed by all nine members that he said they abide by.

Following the latest findings about Alito, Durbin and Sen. Sheldon Whitehouse said in a statement the Judiciary Committee will mark up Supreme Court ethics legislation after the July 4 recess.

"The connection between Supreme Court justices and right-wing billionaires is a very legitimate matter of concern," Whitehouse told reporters.

Sen. Richard Blumenthal, a Connecticut Democrat, said he believes Alito broke the law and should be held accountable.

"Justice Alito violated the plain meaning and spirit of the law in failing to report the trip and his denial now of any possible wrongdoing just shows how the Supreme Court and Justice Alito think they don't have to answer to anyone," he told CBS News' congressional correspondent Nikole Killion.

But Senate Minority Leader Mitch McConnell suggested that Congress cannot dictate the ethical standards of the Supreme Court.

"Congress should stay out of it because we don't, I think, have the jurisdiction to tell the Supreme Court how to handle the issue," he said. "I have total confidence in Chief Justice John Roberts to in effect look out for the court as well as its reputation."

Jack Turman contributed reporting.