HARRISBURG, Pa. (AP) — A neck-and-neck western Pennsylvania state Senate race may hinge on whether the Republican challenger can convince appeals courts that ballots in signed, mail-in envelopes should not count if voters did not also put dates on those envelopes.

Commonwealth Court on Wednesday accepted Nicole Ziccarelli’s appeal and ordered that, for now, Allegheny County cannot count more than 2,300 mail-in ballots without dates on their exterior envelopes.

“The Election Code has clear mandates in it,” Ziccarelli's lawyer, Matt Haverstick, said Thursday. “When we allow freelancing like this, and decisions that are not consistent with the Election Code, we get results that are different throughout the state.”

Ziccarelli is asking to join a case the Pennsylvania high court agreed to hear on Wednesday, in which Republican President Donald Trump's campaign wants more than 8,000 ballots disqualified in Philadelphia because voters who signed their ballots failed to also handwrite their names, addresses or the date.

Ziccarelli is currently down by just 28 votes against incumbent Democrat Jim Brewster, a former banker first elected to the Senate 10 years ago, in a race The Associated Press has not yet called.

With more than 131,000 votes cast in Allegheny and Westmoreland counties, a district that runs down the Alle-Kiski Valley, Brewster's lead is a razor-thin 50.01% to 49.99%.

Ziccarelli also has a lawsuit pending in Westmoreland County that argues elections officials in that part of the Senate district treated mail-in ballots without secrecy envelopes inconsistently and improperly counted some provisional ballots.

In that case, she argues the elections board should not have allowed all votes to count from voters who had to cast provisional ballots and were also directed to sign the poll book. The signatures on a precinct's poll book make it unclear whether those voters also cast a conventional voting machine vote.

Brewster, a former mayor of McKeesport, is the ranking Democrat on the Law and Justice and Game and Fisheries committees. Ziccarelli is a lawyer from New Kensington.

The state Senate is days from the end of its current term, with Republicans holding a 28-21 majority, along with an independent who caucuses with the GOP. A Ziccarelli win would give Republicans a 30-20 working majority in January.