Top-tier Democratic presidential candidates are moving to staff up their teams as they try to gain an advantage in what’s expected to become a crowded field in 2020.

The three main Democratic candidates who have announced in the past month — Sen. Kamala Harris, D-Calif., Sen. Elizabeth Warren, D-Mass., and Sen. Kirsten Gillibrand, D-N.Y., — are all hiring staffers for their bids, according to job postings asking for resumes to fill several positions.