Cook County Board President Toni Preckwinkle will announce this week that she will run for Chicago mayor, sources with direct knowledge of her plans confirmed Monday.

Preckwinkle, who also is chair of the Cook County Democratic Party, is planning an event for 3 p.m. Thursday to make the announcement, according to two sources who spoke directly with Preckwinkle about her plans.

A representative for Preckwinkle’s campaign did not immediately respond to a request for comment.

If she goes through with entering the race, Preckwinkle would become the second high-profile candidate to launch a bid following Mayor Rahm Emanuel’s stunning decision earlier this month to drop his quest for a third term to spend more time with his wife, Amy, and to pursue the “next chapter” of his life. Former Commerce Secretary and onetime White House chief of staff Bill Daley, the brother and son of two former mayors, announced his campaign Monday.