Sen. Bob Casey (D-Pa.) held a commanding lead over Republican Tom Smith in a new poll released by Franklin & Marshall College today.

The poll, which surveyed 412 registered voters from May 29 to June 4, showed Casey leading Smith 42 percent to 21 percent. More than a third of voters said they still remain undecided.

Nearly 30 percent of those surveyed said they did not know enough about Casey to have an opinion about him, despite serving five years in the Senate and coming from a family that has been prominent in Pennsylvania politics for decades.

Smith — a former executive at a coal company — spent more than $3 million of his own money to win the Republican primary in April over the candidate endorsed by the state party. The poll suggested that Smith’s name recognition remains low across the state. More than 75 percent of poll respondents said they did not know enough about him to view him favorably or unfavorably.

Roll Call rates the Pennsylvania Senate race as Likely Democratic.

The poll also gives President Barack Obama a healthy lead over Republican presidential nominee Mitt Romney. Obama would win Pennsylvania 48 percent to 36 percent if the election were held today, the poll found.