The new power couple taking on Wall Street: J.D. Vance and Elizabeth Warren

Sen. J.D. Vance — the Trump-backing former venture capitalist — is trying to lead Republicans in a new cause: cracking down on big banks.

Following a Senate campaign in which he pledged to prioritize rural America over titans of industry, the Ohio lawmaker is using a seat on the Banking Committee to flex his populist bona fides, teaming up with Democrats including Sens. Elizabeth Warren of Massachusetts and Dick Durbin of Illinois on bills that the industry’s biggest players despise — while championing legislation that protects smaller banks.

He’s taking a lead role in advancing bipartisan...