Millionaire businessman Tom Knox will abandon his bid for the Democratic nomination for governor and endorse Allegheny County Executive Dan Onorato as early as this morning.

While Mr. Knox had not made any breakthroughs in early polling in the race, his decision to drop out is a significant boost to Mr. Onorato as the Philadelphia businessman was the only one of his rivals who appeared to have the potential to match his spending power in the crowded Democratic race.

But the candidate's departure was also welcomed by Montgomery County Commissioner Joe Hoeffel, who shares a political base with Mr. Knox in the Philadelphia metro area, home to the state's largest concentration of primary voters.

Lauren Townsend, a strategist for Mr. Hoeffel, said the development was a good thing for his campaign. She said that he was now the only true progressive in the race and noted that he is the only remaining candidate from southeastern Pennsylvania.

Mr. Onorato's campaign has demonstrated acute sensitivity to that political geography. He launched his official announcement tour in Philadelphia, a departure from the more typical political practice of kicking off a campaign before a hometown crowd. Last week, he chose a southeastern Pennsylvania venue to unveil an economic development white paper.

But while Mr. Hoeffel hopes to benefit from his base, he is far behind Mr. Onorato in the cash needed to wage a statewide campaign. Last week, Mr. Onorato said his would report more than $8 million in contributions in its 2009 year-end report. The Hoeffel campaign said he had raised a little more than $400,000.

The Onorato forces will use the development to try to nurture a sense of inevitability about their candidate. The second-term executive has also had early success in gaining backing from party figures and hopes to trot out more endorsements in the coming weeks.

But despite that momentum with the Democratic hierarchy, neither Mr. Onorato nor any of his rivals has yet demonstrated broad support among the Democratic rank-and-file.

Auditor General Jack Wagner, another Democratic contender, rolled to a landslide re-election victory in 2008, but he has run behind Mr. Onorato in early polling. But the biggest numbers in the polls have been in the column of the undecided. In a Quinnipiac University survey in December, Mr. Onorato led with just 14 percent of the Democrats polled. Mr. Hoeffel followed with 8 percent.

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