Jim McGovern JUST SAID IT! Chairing the Rules Committee, he pointed out to Republican Lesko....

[magicarpet]

58. In more recent times we can thank....

... Newt Gingrich for resurrecting the term.

Via WikiPedia:

(begin snip)
During the 1984 Republican National Convention, use of the term was a point of contention among the delegates.[27] When a member of the Republican platform committee asked unanimous consent to change the phrasing of a platform amendment to read Democrat Party instead of Democratic Party, New York Representative Jack Kemp objected, saying that would be "an insult to our Democratic friends;" the committee dropped the proposal.[6]

Newt Gingrich, in his efforts in the 1980s and 1990s to produce a Republican majority in the United States House of Representatives, relied heavily on words and phrases that cast Democrats in a negative light.[28] The phrase Democrat Party gained new currency when the Republican Party, led by Gingrich, gained control of the House of Representatives in 1994.[3]

In 1996, the wording throughout the Republican Party platform was changed from Democratic Party to Democrat Party: Republican leaders "explained they wanted to make the subtle point that the Democratic Party had become elitist".

(end snip)

https://en.m.wikipedia.org/wiki/Democrat_Party_(epithet)