US regional carrier Republic Airways will acquire an additional 30 Embraer 175 regional jets for operation with Delta Air Lines in the coming months, a move that will boost its operations for the US major by some 75%.

As part of the expansion, Republic will also open new employee bases in Boston and Louisville.

Indianapolis-based Republic already operates 38 E175s for Delta and will acquire the additional jets between October and July 2020, it says.

The airline's growth follows Delta's disclosure of plans to transform its regional operation to include only three, not five, regional airline partners.

Within 11 months, Atlanta-based Delta will terminate service contracts with GoJet Airlines and Compass Airlines and expand agreements with remaining carriers Republic, SkyWest Airlines and Endeavor Air.

Republic has not said from where it will receive the 30 E175s and did not immediately respond to a request for more information.

But Delta on 6 August said it plans to shift E175s currently operated by Compass into the fleets of its remaining partners.

Compass operated 36 E175s for Delta at the end of June, according to the latter's second-quarter financial filing.

Republic says it "expects the expansion to increase its scheduled daily operations for Delta by more than 75%".

The carrier currently operates up to roughly 220 flights daily for Delta, with 83% of those departing or arriving at Boston or New York's La Guardia airport, according to Cirium schedules data.

To accommodate the growth, Republic plans in December to open crew and maintenance bases in Boston and a crew base in Louisville, it says.

Republic already has a maintenance operation in Louisville.

Delta will also transfer Bombardier CRJs operated by GoJet to its other partners. GoJet operated 27 CRJs for Delta at the end of June, the financial filing shows.