(CNN) Joe Biden will announce his presidential bid on Thursday with an online video, sources familiar with the plans confirm to CNN, finally answering one of the lingering questions hanging over the 2020 Democratic race.

The former vice president's team has been laying the campaign groundwork for months, with Biden's decision growing less secretive or suspenseful by the day. But now that he has given the green light to his advisers, Biden is facing one of the biggest challenges of his half-century career in politics.

He is scheduled to hold his first campaign event in Pittsburgh on Monday, a source said, and plans to hit the road to the early-voting states of Iowa, South Carolina and New Hampshire in the coming days.

His political action committee, American Possibilities, sent an email to supporters on Tuesday to urge them to sign up for the news.

"We'll cut to the chase," the message said. "There has been a lot of chatter about what Joe Biden plans to do. As one of Joe's top supporters, we want you to be the first to know!"

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