WATCH: Trump’s collusion with Russia is now a topic for impeachment — along with obstruction and racism
MSNBC anchor Lawrence O'Donnell (screengrab)

President Donald Trump's interactions with Russia are now a topic of the impeachment investigation.

"There was an important development in support for impeachment proceedings in the House of Representatives today," MSNBC anchor Lawrence O'Donnell reported Tuesday. "Important both in who the new support comes from and what that support is based on."

"Congresswoman Lauren Underwood of Illinois is one of the freshmen Democrats who flipped a Republican district last year in winning her election. She brings the total number of House Democrats supporting impeachment now to 126 -- a majority of the Democrats' 235 members of the House," he explained.

"She is the first member of the House to issue a public statement in support of impeachment based entirely on Volume I of the Mueller Report. Volume II describes obstruction of justice, including the president’s attempts to fire Robert Mueller, but it is the largely ignored Volume I in the impeachment process that describes the Russian attack on our election and the Trump campaign’s cooperation with Russian interests in the Trump campaign," he explained.

Other members have suggested impeachment for obstruction of justice or racism.

O'Donnell read from Rep. Underwood's statement.

"No one is above the law, including the president of the United States. The Mueller Report lays out substantial evidence that the president’s campaign worked with a foreign adversary to influence an election. The president has stated he would welcome foreign help to win the 2020 election. I find this extremely concerning," she said. "The Mueller report gave us a lot of information, but it left open a lot of key questions that House committees are investigating."

"I have long stated that I support the impeachment-related investigation by Chairman Nadler and the others being pursued by five other committee chairs. The American people deserve all the facts and full transparency and Congress needs this information to inform a decision to move forward with the very sobering act of drafting articles of impeachment. And just as importantly, we need the information to better understand how our election was influenced by a foreign adversary to prevent it from ever happening again," she added.