(Bloomberg) — You won’t find her name on a plaque at the entrance of the D.C. lobbying shop. She’s not on the firm’s letterhead. What Kirsten Chadwick may soon have to show for her skills of persuasion is a U.S.-South Korea free-trade agreement.

Chadwick, a lobbyist at the boutique Republican firm Fierce, Isakowitz & Blalock, is an expert on trade and the treaties that underpin it. She’s seen as a superb vote counter in Washington, tracking the ever-changing yeas and nays on Capitol Hill and knowing when a lawmaker is just being polite or actually promising a vote.

Chadwick represents an array of companies, from Ford Motor Co. to Home Depot Inc. to JPMorgan Chase Bank NA, all rooting for a U.S.-South Korea pact. Trade deals dictate the rules both countries must adopt on patents, banking and telecommunications. With almost $68 billion in trade involved, the deal would be the largest for the U.S. since Nafta in 1994, the pact on which Chadwick began earning her reputation.

Once again she’ll spend a lot of time in the offices of House members trying to secure their votes. “It’s not really even lobbying at this point. It’s education,” she said, referring to Congress’ 100 new members.

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Chadwick started out as an intern in President George H.W. Bush’s congressional liaison office. Her boss, Nicholas E. Calio, was so impressed with the 22-year-old that he brought her to his lobbying shop. The pair returned to the White House under George W. Bush, with Chadwick serving as primary contact with the House Ways and Means Committee, which writes tax laws and approves trade deals.

Chadwick was so involved in passage of the controversial Central American Free Trade Agreement six years ago that newspapers mistakenly reported she was on the House majority whip’s staff.

In recent years, Fierce, Isakowitz resisted adding Democrats. The firm’s deep relationships with Republicans leaders now back in power in the House, boost the odds of the deal with South Korea becoming law by midsummer.