Shareholders of oil and gas producer Unocal have given their preliminary approval to a $17.3bn (£9bn) takeover offer from larger US rival Chevron.
Unocal's board had already backed Chevron's bid
The deal, which is expected to be rubber stamped on 17 August, will pay $30.13 in cash and 0.6 Chevron shares for each Unocal share.
Until last week Chinese oil producer CNOOC was putting forward a rival and higher $18.5bn offer for Unocal.
CNOOC eventually pulled out due to strong political opposition in the US.
Some US politicians said the offer from the state-owned Chinese company posed a potential threat to national security.
This left the way clear for Chevron, whose offer had been approved by the Unocal board on 20 July.