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Senator Bernie Sanders doubled down on his warning to democratic rival Hillary Clinton that her pick for running mate will be critical to winning over his supporters going into the general election during an interview to air Sunday on “Meet the Press.”

“That means having a candidate who can excite working families, excite young people, bring them into the political process, create a large voter turnout,” Sanders told Chuck Todd.

The Vermont senator was adamant that Clinton pick a hardline progressive for vice president if she successfully secures the Democratic nomination for president. This could help her appeal to the supporters who have flocked to Sanders’ campaign during the primary.

Asked whether Virginia senator Tim Kaine, who’s rumored to be on Clinton’s short list, is the kind of running mate he’s recommending, Sanders said, “I really like him very much,” but declined any further speculation.

The full interview airs Sunday on “Meet the Press.”

PLEASE NOTE: Due to NBC Sports programming, "Meet the Press with Chuck Todd" will air at different times this Sunday than its regular schedule in many markets. Revised broadcast times for this coming Sunday can be found here: http://nbcnews.to/1TZfNrM. The show may be pre-empted in some markets but will be available On Demand with video available online at MeetThePressNBC.com.