The National Republican Congressional Committee's independent expenditure unit is cancelling its remaining ad reservation in the Pittsburgh media market through Election Day – a potentially grim sign for Rep. Keith Rothfus Keith James RothfusCNN's Tapper tried to talk GOP candidate out of running against Democratic incumbent: report Lobbying world Conor Lamb gets 2020 challenger touted by Trump MORE (R-Pa.).

The move comes weeks after the NRCC pulled the plug on reservations in the area for Sept. 12-Oct. 8 and could signal that the committee may be losing confidence in whether Rothfus can defeat Rep. Conor Lamb (D-Pa.) in November.

The latest cancellation was announced on Twitter by ad-tracking firm Medium Buying.

NRCC IE has canceled the remaining spending they had in place in the Pittsburgh DMA (was booked for 10/8-11/6)#Done https://t.co/I16V42tMh6 — Medium Buying (@MediumBuying) September 21, 2018

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A spokesperson for the NRCC did not immediately respond to The Hill's request for comment.

Rothfus currently represents Pennsylvania's 12th District, while Lamb represents the 18th. But redistricting in the state changed the current map, pitting both incumbents against one another in a new 17th District in November.

The redistricting has made Rothfus' reelection bid tougher. The Cook Political Report currently ranks the race between the two incumbents as "leaning Democratic," meaning Lamb has a slight edge.

Lamb also benefited from the national media attention he received earlier this year after his stunning special election victory in a district that President Trump Donald John TrumpBiden on Trump's refusal to commit to peaceful transfer of power: 'What country are we in?' Romney: 'Unthinkable and unacceptable' to not commit to peaceful transition of power Two Louisville police officers shot amid Breonna Taylor grand jury protests MORE won by 20 points in 2016.

A Monmouth University poll from July showed Lamb with a 12-point lead over Rothfus.