HARRISBURG, Pa. - Tom Wolf is maintaining a large lead in the Democratic race for Pennsylvania governor, but there are more undecided voters, according to an independent statewide poll released Thursday.

The poll by Franklin & Marshall College in Lancaster showed that 46 percent of Democratic voters were still making up their minds. That is about what the same pollster found in a late February survey.

Wolf, a York County businessman whose largely-self-funded campaign has been airing nonstop TV ads since late January, claimed 33 percent of the voters surveyed. U.S. Rep. Allyson Schwartz of Montgomery County had 7 percent, state Treasurer Rob McCord of Montgomery County had 6 percent and former state environmental protection secretary Katie McGinty of Chester County had 4 percent.

The poll revealed that a growing number of voters are noticing the TV ads aired by Wolf, McCord and McGinty. Seventy-one percent of Democratic voters said they had seen a commercial for governor, up slightly from the February poll. Schwartz has yet to air a TV ad.

Education was cited most frequently as an issue registered Democratic Party voters said they would consider in choosing a nominee. That was followed by the economy, according to the poll.

The poll results do not include questions about Republican Gov. Tom Corbett, who is seeking a second four-year term and is being challenged in the primary by suburban Philadelphia businessman Bob Guzzardi. The primary election is May 20.

Franklin & Marshall's telephone survey of 524 registered Democratic voters was conducted between March 25 and 31. The poll's margin of sampling error was plus or minus 4.3 percentage points.