Pennsylvania -- Katie McGinty

The Pennsylvania race could serve as a double whammy to Wall Street if Toomey loses, because it would mean gaining a lawmaker who appears to be part of Elizabeth Warren’s growing political posse. Warren has aggressively campaigned and raised money for McGinty. At political events, they regularly discuss their shared desire to strengthen financial reforms.

Attacking Toomey’s ties to Wall Street has been one of McGinty’s main lines of attack. She has continuously lambasted him for his campaign contributions, his past finance career and how a bank he invested in allegedly forced small business owners out of their homes.

Nevada -- Catherine Cortez Masto

Democrat Catherine Cortez Masto in Nevada is another candidate that stands out as a potential ally of Warren’s. Throughout her campaign, she frequently cites how during her tenure as the state’s attorney general, she held Wall Street banks accountable. She sued Bank of America Corp. over deceptive foreclosure practices during the financial crisis and her office investigated more than 200 companies for mortgage fraud. Wall Street lobbyists fear her background could make her a contender to join the Senate Banking Committee.

Masto is running against Republican Joe Heck, currently a U.S. representative from the state’s third congressional district.

Indiana -- Evan Bayh

Should Democrats take control of the Senate, bank lobbyists will be looking to moderates to help blunt Warren’s clout and provide balance on the banking panel, which is expected to be chaired by Sherrod Brown, a progressive Democrat from Ohio.

Democrat Bayh, who is running in Indiana, fits the mold. Bayh, considered a centrist, is looking to reclaim his seat after retiring from Congress in 2010. Since he left office, he’s been a lobbyist in Washington, an adviser to the private equity giant Apollo Global Management and sits on the board of Fifth Third Bancorp.

Should he win and return to the banking committee, lobbyists expect he’d be more likely to work across the aisle and be receptive to Wall Street’s issues. He’s currently leading in polls against Republican Todd Young.