Democratic Rep. Al Green (Texas) called on President Trump to declare a national emergency in order to implement a buyback program for "long guns" on Wednesday during a television appearance on CNN.

"The president can do more," Green told CNN host John Berman. "He could declare a national emergency. He can then take up the issue of buybacks for these guns, weapons of mass destruction, as it were, when it comes to long guns."

All rifles and shotguns are considered to be long guns. Green went on to say he believed so-called "assault weapons" should be banned.

"We do have to ban these assault weapons," he said. "They are taking lives across this country. So, we should do this."

The definitions of "assault weapon" vary in the handful of states which have banned their sale but are always a smaller subset of long guns—despite often including some of the most popular rifles in the country.

Rep. Green said banning "assault weapons" or buying back long guns would not be a sufficient response, though. Instead, he renewed his call to impeach President Trump.

"But I don't think that this is enough, to be quite candid," he said later in the interview.

"The vice president was on just before I had this opportunity to come on, and he made the case," Green said in reference to former Vice President Joe Biden's speech in Iowa Wednesday afternoon. Green added that he believes Biden's speech "made the case for impeachment."

"This president must be impeached. To defeat him at the polls will do history a disservice, would do our nation a disservice, and would not allow us to do what they did in 1868 when Andrew Johnson, who was the bigot of his time, was impeached by the radical Republicans," Green continued. "There ought to be radical Democrats and Republicans willing to rise to the occasion and say to this president, you are unfit, unworthy, and you must be removed from office."

The Texas congressman has been one of the most vocal proponents of impeaching President Trump and in 2017 was the first member of Congress to publicly call for the impeachment of the President on the House floor.