Elizabeth Warren and her liberal allies appear to be on the verge of another victory in their battle to stop the White House from choosing financial regulators with ties to Wall Street. President Barack Obama was planning to nominate corporate attorney Keir Gumbs to fill a Democratic seat on the Securities and Exchange Commission last month, according to four sources familiar with the matter. But now that’s on hold at least until August after activist groups aligned with Warren raised an outcry over Gumbs’ work, including his advice to companies on how to dodge scrutiny from shareholder activists.