Washington (CNN) Democratic Sen. Mark Warner of Virginia suggested Sunday that Donald Trump Jr.'s reported meeting with a Gulf emissary who offered to help his father's presidential campaign could be evidence of a larger pattern of concern.

"If the Times story is true, we now have at least a second and maybe a third nation that was trying to lean into this campaign," Warner, the vice chairman of the Senate Intelligence Committee, said on CNN's "State of the Union." "I don't understand what the President doesn't get about the law that says if you have a foreign nation interfere in an American election, that's illegal."

Warner's comments follow a New York Times report Saturday that said three months before the 2016 presidential election, Trump Jr. met with a small group of people at Trump Tower in New York, including an emissary for two Arab princes and an Israeli social media specialist, who offered assistance to the Trump campaign, several people with knowledge of the encounters told the paper.

The story prompted criticism from President Donald Trump on Twitter Sunday morning. Trump wrote in a series of tweets that the piece was "long & boring" and that it indicates "that the World's most expensive Witch Hunt has found nothing on Russia & me so now they are looking at the rest of the World!"

"Now that the Witch Hunt has given up on Russia and is looking at the rest of the World, they should easily be able to take it into the Mid-Term Elections where they can put some hurt on the Republican Party," another tweet said.

The Times identified the Gulf emissary as George Nader, a Lebanese-American businessman, and reported that he informed Trump's son "that the crown princes who led Saudi Arabia and the United Arab Emirates were eager to help his father win election as president."

The newspaper reported that the social media expert and Israeli, Joel Zamel, talked about how his company could help a political campaign gain an advantage. According to the Times, the company had by then put together "a multimillion-dollar proposal for a social media manipulation effort to help elect Mr. Trump."

It is unclear, however, whether a proposal was ever executed, and details on who commissioned it remain in dispute, the Times reported.

On Sunday, Warner also said he would like to understand whether the reported meeting was indicative of a pattern that should be investigated.

"There's this pattern that other countries were offering, and clearly the Trump campaign was receptive to these kinds of offers -- how that is not the beginnings of evidence of stuff that needs to be investigated," he said.

The House Intelligence Committee's ranking Democrat, California Rep. Adam Schiff, also said Sunday that the specifics of the meeting with the Gulf emissary, as they were described by The New York Times, "were certainly new" to his committee.

"If these facts are accurate, it demonstrates yet again just how not only willing, but eager the President's son and the Trump campaign were to solicit to receive foreign help," Schiff said on NBC's "Meet the Press."

Special counsel Robert Mueller is investigating another Trump Tower meeting involving Trump Jr. and other Trump campaign associates, including the President's son-in-law, Jared Kushner, and his former campaign chairman Paul Manafort, as well as a Russian lawyer with ties to the Kremlin. That meeting took place in June 2016 after Trump Jr. was told that the crown prosecutor of Russia wanted to give incriminating information about Hillary Clinton to the Trump campaign.

The Russian lawyer, Natalia Veselnitskaya, focused on US sanctions on Russia under the Magnitsky Act, which the US passed to punish Russians over human rights abuses, as well as "the adoption of Russian children by U.S. citizens," Trump Jr. told the Senate Judiciary Committee in September.

"I did not collude with any foreign government and do not know of anyone who did," Trump Jr. told the panel, according to a transcript.