Occidental Petroleum Corp. Chief Executive Officer Vicki Hollub is on the cusp of winning a David versus Goliath bidding war that has captivated the oil industry.

After making a series of approaches to rival Anadarko Petroleum Corp. about a merger over almost two years, Hollub was blindsided last month when the company embraced a takeover offer from Chevron Corp., despite it being considerably lower than her $38 billion bid.

The University of Alabama-trained engineer didn’t back down. In a series of bold and creative moves that included securing a $10 billion investment from Warren Buffett, Hollub is back in pole position in the battle for Anadarko. In gaining the stamp of approval from Anadarko’s board on Monday, she has boxed Mike Wirth, her counterpart at Chevron, into a corner with the uncomfortable choice of tarnishing his reputation for financial conservatism or conceding defeat.

“Hollub is ripping up the playbook and running an all-out offense on the Anadarko board to favor her bid,” Mizuho Securities analyst Paul Sankey said.

Three moves have been key to Hollub’s ascendancy in the biggest oil-industry bidding war in years. First, she flew to Omaha to explain the deal’s benefits to Buffett and returned with a huge investment.