March 13 (UPI) -- Democrats eyeing control of Congress this fall have another opportunity Tuesday to gain a seat, when Pennsylvania voters choose a replacement for former Rep. Tim Murphy.
Tuesday's special election between Republican Rick Saccone and Democrat Conor Lamb is also expected to serve as a preview of other national races for November's midterm elections.
The two candidates in Pennsylvania's 18th district are vying to fill the House seat vacated by Murphy who resigned in October following a scandal involving a staffer.
The winner Tuesday will serve out the remaining 10 months of Murphy's term, but will have to win a new district to be re-elected in November -- because of an anti-gerrymandering decision last month by the Pennsylvania Supreme Court that realigned congressional districts.
Heading into Tuesday's vote, polling showed Lamb with a slight edge in the district -- considered Republican territory in southwest Pittsburgh, where President Donald Trump beat Democrat Hillary Clinton by nearly 20 points in 2016.
Last weekend, Trump attended a campaign rally in Pennsylvania for Saccone.
Democrats have performed respectably in special elections in the last year -- but have picked up only one seat in Congress since Trump's election in November 2016 -- Alabama's Doug Jones, who defeated Roy Moore for Jeff Sessions' vacant Senate seat.