The county Republican parties within the district have all appointed representatives to the meeting tonight -- these representatives are called "conferees" -- apportioned on the basis of how many votes John McCain won in the portions of each county that are within the district. There are a total of 134 conferees, and these are the people who will select the candidate.
At tonight's meeting, each candidate will get to make a presentation of up to five minutes, followed by a question-and-answer session of up to ten minutes. The press will be permitted in the room to see the whole process. Finally, the conferees will take a roll-call vote -- not a secret ballot -- and a candidate who receives a majority of the votes will be nominated.
A Republican source told TPMDC that Burns is the favorite to win the nomination, as he has a business background in the district, whereas Russell is not originally from the district (he moved there to challenge Murtha in 2008, due to Murtha's anti-war advocacy), and is not seen as a good fundraiser.
The source also said that the election here will be tough for the GOP. The special election is scheduled for the same day as the statewide Pennsylvania primary. Democrats have many more competitive races in their primaries this year than the Republicans do, and those campaigns could spur Democratic turnout in the district.
The district was carried very narrowly by John McCain in 2008 -- the only district in the country to switch from the Democratic column in 2004 to the Republicans in 2008 for the presidential vote, after having been carried 51%-48% by John Kerry.
Democrats have already nominated Mark Critz, a former chief of staff to Murtha, through their own internal process that involved local party committees and the state party executive committee.