Voters in Colorado headed to the polls on Tuesday to cast ballots in the state's primary elections. File Photo by Bonnie Cash/UPI | License Photo

July 1 (UPI) -- Progressives had a big night in Colorado's primaries Tuesday, led by lawyer Melat Kiros, who was poised to unseat 15-term incumbent Rep. Diana DeGette for the Democratic nomination in the state's 1st Congressional District.

With votes still being counted late Tuesday, Kiros had secured 51.3% of the vote, compared with DeGette's 41.6% and Wanda James' 7%, according to preliminary results from the Denver government.

If the tallies hold, Kiros' victory would be a surprise upset, and would mark another establishment Democratic incumbent losing to a progressive.

The 29-year-old democratic socialist claimed victory during a speech before supporters Tuesday night.