(CNN) Sen. Bernie Sanders has hired Faiz Shakir, a respected progressive operative who had been serving as the national political director for the American Civil Liberties Union, to manage his presidential campaign, an aide told CNN on Tuesday.

Shakir previously worked as an adviser to former Senate Democratic Leader Harry Reid of Nevada and, before that, then-House Minority Leader Nancy Pelosi. He joined the ACLU in January 2017, as President Donald Trump took office, and has emerged as a leading voice in a series of high-profile legal battles against the administration.

Sanders' decision to hire Shakir, who has credibility across the Democratic party's establishment-progressive insurgent divide, is a sign that the organization behind his second bid for the Democratic nomination will be more robust following a campaign that struggled to build a national infrastructure on the fly in 2016.

Shakir replaces Jeff Weaver, Sanders' first presidential campaign manager, who will stay with Sanders as a senior adviser.

"Faiz is a diehard progressive who knows how to work effectively within the system," Adam Jentleson, Reid's former deputy chief of staff, told CNN on Tuesday. "Reid did not make a big decision without consulting Faiz. There's no one he trusted more on how the progressive community would react on something and no one whose advice he took more seriously on pushing him to the left."

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