Washington (CNN) Connecticut Gov. Dannel Malloy has decided not seek a third term in 2018, a source familiar with his decision told CNN.

Malloy, the chairman of the Democratic Governors Association, is set to announce his decision at a Thursday afternoon news conference in Hartford.

The 61-year-old has been a leading national voice for gun control laws following the 2013 shooting at Sandy Hook Elementary School in Newtown.

Now, Malloy is among the leaders of a new Democratic group headed by former Attorney General Eric Holder that's set to focus on redistricting in court battles and state legislative races.

Malloy's name has regularly appeared on lengthy lists of potential Democratic 2020 presidential candidates.

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