General Motors Co's flagship Chevrolet brand expects to boost sales driven by new launches such as the Cruze small car and may represent 70 percent of the automaker's North American sales, the brand's chief said on Friday.

GM GM.UL is under enormous pressure to reverse a long-running slide in sales as it aims to steer itself toward recovery and pay back taxpayers after emerging from bankruptcy in July with some $50 billion in U.S. government funding.

Chevrolet will carry the burden of driving GM's sales and market share after the top U.S. automaker eliminates four of its eight brands. It plans to sell its Hummer and Saab brands and close Saturn and Pontiac.

Globally, Chevrolet has the challenge of picking up sales from GM's European Opel brand, which is being sold to Magna International (MGa.TO), and increasing its presence in emerging markets like China, India and Eastern Europe.

It's (Chevrolet) going to take on a larger role as we go from eight brands to four, Brent Dewar, who was named vice president of Chevrolet in July, told Reuters in an interview. Here in North America we are going to be responsible for 70 percent of volumes.

As Pontiac goes away, Saturn goes away, Chevrolet has to step up. That's clear, Dewar said. The 70 percent target is the right kind of number we need to work on.

Chevrolet has represented more than 60 percent of GM's sales so far in 2009, compared to 54 percent in 2002. Globally, it accounts for more than half of the automaker's sales.

GM's U.S. sales plunged 45 percent in September from a year earlier. Its U.S. market share including brands being scrapped was 19.5 percent, down from 22.1 percent at the end of 2008.

Despite the reduced number of brands, Dewar said GM aims to boost its U.S. market share in coming years with new products such as the Chevrolet Cruze small car and Chevrolet Volt electric car. Both are slated to hit showrooms next year.

Maintaining the status quo would not be acceptable to (CEO) Fritz Henderson and our board, Dewar said.

He said October industry-wide U.S. auto sales are trending better than September, when the seasonally adjusted sales rate fell to 9.2 million units, the weakest sales rate since April.

U.S. auto industry sales are expected to come in at 10.2 million to 10.5 million vehicles in 2009 and to increase by at least 10 percent from there next year, Dewar said.

(Reporting by Soyoung Kim)