Rep. Denny Heck (D., Wash.) told CNN host Kate Bolduan on Tuesday that the Trump campaign's involvement with Russia has now gone "far past collusion," and called on the Trump administration to come clean.

The House Intelligence Committee member brought up the Watergate scandal that sunk former President Richard Nixon's administration and said President Donald Trump has found himself in a similar position. Heck stopped short of calling for impeachment, however, and said administration officials should tell the whole truth.

"My advice to him is that it is far past time to come clean," he said. "If there's anything we have learned in the last six months, it's that the truth will be out."

Donald Trump Jr. created a firestorm of controversy when it was revealed that he and other campaign officials met with a Russian lawyer to get information on Hillary Clinton during the 2016 campaign. Heck maintained that what has come out so far has already proven some level of collusion with Russia.

"Frankly, Kate, we are far past collusion," he told Bolduan. "That's one of the charges of the Intel Committee, to seek out whether or not there was collusion with the Russian government with respect to the efforts to interfere in our 2016 presidential election. We are far past that, at this stage."

Bolduan then asked what they are at, if they are past collusion.

"We are at the point where, as I said earlier, it's far past time for this administration to come clean," Heck answered. "This is getting very serious, Kate. Look, I do not believe that articles of impeachment should come before an investigation is complete, and we are at the beginning or near the middle of ours."

"I think it is ominous and should be ominous to the president of the United States that the percentage of Americans calling for impeachment is almost double what it was at this stage of the Watergate era," Heck added.

He likened the administration's situation regarding the Russia investigation to a cancerous tumor. He took that image from Nixon's counselor during Watergate.

"In particular this week I thought what resonated with me was a quote by Nixon's counselor, his chief attorney, who at one point said, ‘Mr. President, there is a cancer growing on your presidency,'" Heck said. "That's the case here."

"It's far past time to come clean. It would be the political equivalent of chemotherapy if they did," he added, continuing the cancer analogy.

He also criticized White House senior advisor Jared Kushner's actions while getting in a dig at the GOP's recently dropped health care bill.

"Jared Kushner's story has changed more often than the Republican health care bill, and we know that every time it changes it gets worse," Heck said.