By Jarrett Renshaw

Washington state plans to require electric vehicle charging companies to include Tesla's plug if they want to be part of a state program to electrify highways using federal dollars, an official told Reuters on Thursday.

Washington follows the move by Texas to mandate Tesla's technology, The North American Charging Standard (NACS), adding momentum to CEO Elon Musk's hope of making it the national charging technology.

GM, Ford and Rivan have said they would embrace Tesla's NACS, shunning efforts by the Biden administration to make the Combined Charging System (CCS) the dominant charging standard in the United States.

"I’m actually really happy about NACS and how finally automakers are gearing towards one standard. We want to provide access to as many makes and models as possible," said Tonia Buell, alternative fuels program manager at Washington state's Department of Transportation.

"It hasn't necessarily been tested and certified for other auto manufacturers, so we want to make sure it's going to work but we are planning to require NACS at our state funded and federally funded sites in the future."

The state plans to begin the requests for proposals process in the fall.

Buell said the decision is about “future proofing” the state’s investments.

Buell said state officials are still trying to determine the right mix of NACS chargers based on current federal requirements. Under federal rules, each taxpayer-backed site must have at least four CCS chargers and Buell said the state may require at least two of them to work with NACS or perhaps all four.

The plan by Washington may add pressure on other states and the federal government to adopt Tesla's NACS.

(Reporting by Jarrett Renshaw, Writing by Hyunjoo Jin; Editing by Peter Henderson and Daniel Wallis)