Ex-AOC Chief of Staff Saikat Chakrabarti Explains Why He's Challenging Nancy Pelosi

Saikat Chakrabarti is running to unseat Nancy Pelosi in San Francisco -- which may sound sacrilegious to Democrats -- but he says the old guard's time is up ... because Americans want drastic new ideas.

Saikat, a tech millionaire who was Alexandria Ocasio-Cortez's first chief of staff, joined us on "TMZ Live" Thursday and told us why he's challenging Pelosi for her seat in Congress.

The way Saikat sees it ... Nancy was the perfect politician for the days of old, when she gathered bipartisan support to pass legislation, but he says the landscape is drastically different and it's time to inject the Democratic Party with new ideas and new faces.

Saikat says voters want massive economic reforms ... based on what we've seen in presidential elections and the NYC mayor race -- and Democrats like Pelosi just aren't offering what the people crave.

It's interesting ... he sees similarities between the MAGA movement and Democratic Socialists, and tells us where the two extremes line up.

Nancy's not going to be easy to topple ... but Saikat sounds confident he will be able to inject as much money in the race as she will -- so she may be in for a dogfight.