Blackstone Group LP has emerged as the frontrunner in an auction for Allscripts Healthcare Solutions Inc , but the two sides remain far apart on valuation, and a deal is highly uncertain, people familiar with the matter said.

The New York-based buyout firm has prevailed over rival private equity suitors Carlyle Group LP and TPG Capital Management LP in the race to buy healthcare technology company Allscripts, which has a market value of around $2 billion, three people said this week.

Still, Blackstone is skeptical about the prospects of a deal, given the high premium sought by Allscripts and other challenges facing the company, they said.

Sources told Reuters earlier this month that Blackstone, Carlyle and TPG made second-round bids for Allscripts, after the company reported third-quarter earnings.

The people asked not to be identified because the matter is not public.

Allscripts, TPG, Blackstone and Carlyle declined to comment.

Shares of Allscripts fell more than 11 percent to $10.96 on the Nasdaq on Friday. The company had closed trading at $10.88 on September 27, the day before news of a potential sale emerged.

Allscripts said on November 8 that it was evaluating strategic alternatives, following potential buyout interest and that it had enlisted Citigroup Inc to assist with the process.

But the sale process proved challenging, with interested parties concerned about Allscripts' declining earnings and market-share losses to larger rivals, such as Cerner Corp , people familiar with the matter have said.

Allscripts has struggled to boost new business following its ill-proven acquisition of Eclipsys Corp in 2010. The company had hoped to expand into software and equipment for hospitals and health-care systems with the purchase of Eclipsys but ended up losing business to Cerner and closely-held Epic Systems Corp.

Blackstone is an experienced investor in the sector. In April 2011, the private equity firm bought healthcare IT provider Emdeon Inc for $3 billion.

(Editing by Matthew Lewis and Bernadette Baum)