NEW YORK (CBSNewYork) — The Mets are not satisfied.

Just a game behind the first-place Nationals in the National League East, general manager Sandy Alderson is looking to acquire a big bat before the July 31 non-waiver trade deadline.

READ MORE: Harlem's Josephine Baker About To Be Given France's Highest Honor, A Resting Place In The Pantheon

According to baseball insider Jon Heyman, the Mets are still targeting Justin Upton, Carlos Gonzalez, Carlos Gomez, Gerardo Parra and Jay Bruce.

Heyman reports that talks between the Mets and Padres regarding an Upton deal broke down, but they could start up again. Gonzalez is also available, according to Heyman, though the Rockies might choose to wait until the winter to trade him.

READ MORE: First Responders Pay Tribute To Sean Patrick Carroll, Volunteer Firefighter Killed In Thanksgiving Day House Fire

Both Gonzalez and Gomez will cost a lot, Heyman reports, and the Mets do not intend to trade any of their “big four” starters (Jacob deGrom, Matt Harvey, Noah Syndergaard and Steven Matz).

Heyman also notes that, at one point, the Reds were interested in acquiring Mets pitcher Zack Wheeler in a deal for Bruce. Wheeler, who underwent Tommy John surgery in March, has not pitched this season.

A fallback option for New York is Reds outfielder Marlon Byrd, who played for the Mets in 2013.

MORE NEWS: Attorney General's Office Releases Another Round Of Transcripts In Andrew Cuomo Investigation

Alderson has been very active during the trading season, acquiring infielders Kelly Johnson and Juan Uribe last week and trading for relief pitcher Tyler Clippard on Monday.