By Mike Stone and Greg Roumeliotis

(Reuters) - Private equity firm Blackstone Group LP <BX.N> is in advanced discussions to acquire Acrisure LLC, in a deal that could value the U.S. insurance brokerage at well over $2 billion, including debt, according to people familiar with the matter.

Blackstone has so far prevailed in the auction for Acrisure, though negotiations with the company's owner, buyout firm Genstar Capital LLC, are still continuing, the people said this week.

There is no certainty that Blackstone and Genstar will reach a deal, and Genstar may resume negotiations with one of the other private equity firms that bid for Acrisure, the people added.

The sources asked not to be identified because the negotiations are confidential. Blackstone, Acrisure and Genstar declined to comment.

Based in Caledonia, Michigan, Acrisure provides insurance coverage in a swath of sectors, from retail to energy and real estate, in 23 U.S. states. The company generated revenue of $231 million for the 12 months through September 2015, according to Moody's Investors Service.

Reuters reported in January that Acrisure had been working with investment bank Evercore Partners Inc <EVR.N> on a sale process.

Genstar, which specializes in investments in financial services as well as the healthcare, software and life science industries, bought Acrisure for an undisclosed sum in 2013.

Private equity-owned insurance brokerages saw a spate of deals in recent years. Buyout firm Apax Partners LLP, for example, agreed to acquire AssuredPartners Inc in 2015 from GTCR LLC, while Stone Point Capital LLC invested in KKR & Co LP's <KKR.N> Alliant Insurance Services.

(Reporting by Mike Stone and Greg Roumeliotis in New York; Editing by Bernard Orr)