Quote: As its relationship with Democrats hits a historic low, Wall Street sees a solution on the horizon: Hillary Rodham Clinton.

Mrs. Clinton was the industry's home state senator, and the financial sector was the second-largest giver to her presidential campaign in 2008. In her post-State Department life, she has been showered with lucrative speaking fees from Goldman Sachs, J. P. Morgan and other financial firms. In her talks, she says it is unproductive to vilify the industry, and she avoids the kind of language that puts off financial executives, as when President Obama referred to "fat cat" bankers in 2009.

But as Wall Street hopes for a warm embrace from the former secretary of state, Mrs. Clinton must grapple with a populist surge coursing through politics, on both the right and the left.

Attacks on Wall Street bailouts are a staple of Tea Party campaigns. Republicans, many of whom deliberately stood on the sidelines during the legislative battle over the Dodd-Frank legislation and have quietly reaped the benefits of Wall Street's disenchantment with Mr. Obama, are now reeling from the primary election defeat of Representative Eric Cantor of Virginia, the former majority leader. Mr. Cantor's opponent, David Brat, won in part by attacking Mr. Cantor's ties to the financial world.

In Mrs. Clinton's years away from politics, income inequality has become a defining political issue in the Democratic Party, elevating a new generation of stars like Senator Elizabeth Warren of Massachusetts, who has pushed for the breakup of large financial institutions.

Late last month, Ms. Warren campaigned in Kentucky for Alison Lundergan Grimes, the Democratic candidate for Senate, a sign that some in the party believe the Massachusetts senator's message resonates well beyond the left. (Mrs. Clinton has not yet campaigned on behalf of Ms. Grimes, though an adviser said she will likely do so this fall.)

"I think there's a potential window for Democrats to come back, but if it is one wing of the party pushing the populist line — anti-big banks, punishing people whether or not they had anything to do with the crisis — they'll lock this crowd into a Republican alternative," said Bill Daley, a former chief of staff to Mr. Obama and commerce secretary under President Bill Clinton who is now a hedge fund executive.