Senate Democrats are losing their fundraising edge on Wall Street, seeing less money for candidates at a time when the party’s liberal wing is demonizing billions of dollars in taxpayer bailouts to banks. The Democratic Senatorial Campaign Committee (DSCC) raised $10.4 million through the first three months of this year, compared with $9.6 million raised by its Republican counterpart during the same quarter. That’s a much narrower margin than last election cycle, when the DSCC raised $163 million compared to the National Republican Senatorial Committee’s (NRSC) $94 million. The DSCC’s edge has all but vanished since Sen. Charles Schumer (D-N.Y.),...