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A growing number of Democratic senators are saying it's time for House Speaker Nancy Pelosi, D-Calif., to submit the articles of impeachment against President Donald Trump to the Senate.

"We are reaching a point where the articles of impeachment should be sent," Sen. Richard Blumenthal, D-Conn., told reporters Wednesday.

In an interview with MSNBC's Andrea Mitchell on Tuesday, Sen. Angus King, a Maine independent who caucuses with the Democrats, said he believes "it is time for the speaker to send" the articles.

"I don't think her holding them puts any particular pressure on" Senate Majority Leader Mitch McConnell, R-Ky., King said. "I think the key vote will come in the middle of the trial."

Meanwhile, Sen. Doug Jones, D-Ala., told CNN on Tuesday in remarks confirmed by NBC News that he is "hoping" Pelosi will soon submit the articles, although he is still concerned about an agreement to hear from witnesses during the Senate trial.

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Sens. Chris Murphy, D-Conn., and Joe Manchin, D-W.V., both told The Washington Post on Tuesday that they believe it's time to transmit the articles.

Manchin told MSNBC on Wednesday, "The sooner we receive this, the sooner we can find out if we're going to have a real trial or not."

So far, Pelosi is standing firm, continuing to withhold the articles until the Senate process is explicitly laid out, though she suggested she could soon submit them.

"Soon, the Senate will have the opportunity to honor its oath to 'do impartial justice according to the Constitution and laws,'" Pelosi wrote in a letter to colleagues Tuesday before arguing that the process proposed by McConnell is unfair.

No trial can begin until the articles are sent.

"It is important that [McConnell] immediately publish this resolution, so that, as I have said before, we can see the arena in which we will be participating, appoint managers and transmit the articles to the Senate," Pelosi said.

McConnell has said he wants the Senate to conform to the process from former President Bill Clinton's 1999 impeachment trial, which amounted to a two-step process: first, an initial agreement to hear the case and then a later vote to decide whether to call witnesses.

Senate Minority Leader Chuck Schumer, D-N.Y., has pushed for a single resolution that would set parameters for presenting the case and for the calling of witnesses. Schumer wants the Senate to call four witnesses to testify about Trump's conduct toward Ukraine, including former national security adviser John Bolton, who announced this week he would testify if subpoenaed, and acting White House chief of staff Mick Mulvaney.

McConnell, who in December vowed "total coordination" with the White House on the impeachment trial proceedings, said Tuesday he has the votes to set the process he desires.

On Wednesday, McConnell said questions about witness testimony will be raised "at the appropriate time," adding, "Now, even fellow Democrats are expressing public concern over the speaker's endless appetite for these cynical games."

Last month, the House approved the two articles of impeachment against Trump. The first charged him with abusing his power by trying to press Ukraine to announce investigations into former Vice President Joe Biden, his son Hunter and Democrats, and withholding nearly $400 million in military aid to that country, as well as an official White House visit for Ukrainian President Volodymyr Zelenskiy as he pursued those probes. The second article charged Trump with obstructing Congress' efforts to probe the matter.

"The important thing to me is getting to the facts," King said Tuesday. "I think it's going to be very hard for somebody to vote against calling witnesses — particularly, again, someone like John Bolton, who's indicated willingness to come in."