(Reuters) - Southwest Airlines Co will soon begin flying to Hawaii from California, as part of the budget-friendly carrier’s push to boost leisure travel from the West Coast, an executive said on Friday.

FILE PHOTO: Southwest Airlines planes are seen at LAX airport in Los Angeles, California, United States, October 22, 2015. REUTERS/Lucy Nicholson

Southwest’s new service will include inner-island travel in direct competition to Hawaiian Airlines, as well as a combination of flights from Oakland, Sacramento, San Diego and San Jose to four destinations in Hawaii.

Southwest, already a go-to airline for many travelers within California with over 60-percent market share, has been trying to expand its West Coast leisure portfolio under a growth drive that has also included new flights to Mexico.

“Hawaii allows us to give more leisure options to our customers on the West Coast, which has been heavy on the business side,” Andrew Watterson, chief revenue officer for Southwest, said in a phone interview.

That contrasts with Southwest’s portfolio on the East Coast of the United States, where it has built a reputation as a low-cost carrier for leisure destinations in Florida from cities in the U.S. Northeast.

The Hawaii launch comes later than Southwest had hoped after a partial U.S. government shutdown earlier in the year delayed the certification process needed for new over-ocean flights.

As a result, the Dallas-based carrier missed a key booking window for travel to the Hawaiian islands, which Watterson said passengers tend to reserve months in advance, rather than days or weeks.

This means Southwest will have to offer lower-than-average introductory fares through mid-June to stimulate passenger traffic.

“After that we’ll have the traditional Southwest low fares in the subsequent booking period,” Watterson said.

While the government over-water certification opens the door for other long-haul flights for Southwest, Watterson said the plan is to focus on Hawaii for the time being, noting that there is no extra aircraft right now to service new routes.

Southwest will begin flying to Hawaii with its Boeing 737-800 NG planes and plans to switch to 737-MAX 8 aircraft later this year, he said.

The launch comes as Southwest grapples with a bitter labor dispute with its mechanics union that has led to a spike in out-of-service aircraft, forcing flight cancellations and delays.

Southwest’s shares closed 3 percent lower on Friday, giving up gains booked a day earlier which were fueled by speculation that Warren Buffet’s Berkshire Hathaway, the carrier’s second largest shareholder, could be looking to acquire the airline.

Southwest and Berkshire declined to comment on the rumor.