(Reuters) – Anadarko Petroleum Corp said on Monday it would negotiate with Occidental Petroleum Corp over its $38 billion cash-and-stock bid, after determining it could get a better deal than its agreed $33 billion sale to Chevron Corp.

FILE PHOTO: The Occidental Petroleum Corp headquarters is pictured in Los Angeles, California September 16, 2013. REUTERS/Mario Anzuoni

The development represents a breakthrough in Occidental Chief Executive Vicki Hollub’s two-year effort to buy Anadarko, one of the top U.S. oil and gas producers in the lucrative Permian Basin in Texas and New Mexico. Anadarko announced a deal with Chevron on April 12 after snubbing a higher bid from Occidental, prompting Occidental to try to upend the Chevron deal.

“We hope Anadarko will proceed quickly to secure this