The state Supreme Court has granted an emergency appeal from Carl Romanelli, the Republican-financed Green Party candidate for the U.S. Senate, that could secure his place on the November ballot, a prospect that's being fought by Democrats who see his presence as a threat to Treasurer Bob Casey's challenge to Sen. Rick Santorum.

Mr. Romanelli is challenging a Commonwealth Court ruling that upheld an unusually high 67,000-signature threshold for independent candidates seeking a spot on the ballot.

State law specifies that an independent's nominating petitions must include a signature total equal to 2 percent of the votes collected by the highest vote-getter in the previous statewide election. Election officials, in a decision endorsed by Commonwealth Court, said that means Bob Casey's 2004 election landslide for treasurer is the base for the calculation.

Mr. Romanelli's legal team is arguing that a 2005 judicial retention election, with a much lower turnout, should have been used, resulting in a much lower signature requirement.

The case could be crucial to the Senate election. Lawyers for the Democratic Party are trying to keep Mr. Romanelli off the ballot for fear the Green candidate, who favors abortion rights and an immediate withdrawal of American troops from Iraq, might siphon liberal votes from Mr. Casey. The same analysis led GOP donors, reportedly with the active encouragement of the Santorum campaign, to fund the signature drive for Mr. Romanelli's nominating petitions.

Lawrence Otter, Mr. Romanelli's attorney, said his legal fees are being paid by the Green Party. The Santorum campaign did not immediately respond to a question on whether Republicans were financing Mr. Romanelli's legal fees.

The Supreme Court asked for briefs by Sept. 28 on the question of which election should be used for the signature calculation.

It's uncertain whether Commonwealth Court will have ruled by then on whether Mr. Romanelli would qualify for the ballot under the tougher standard. A hearing there resumes Monday.

Mr. Romanelli originally submitted petitions which, by his calculation, included roughly 100,000 signatures, well over the 67,000 requirement.

Democrats contended those petitions were full of signatures for people who were not qualified voters. After poring over the documents line by line, they contend they have found more than enough flawed signatures to have them thrown out.