WASHINGTON—Securities and Exchange Commission Chair Gary Gensler is set to defend his regulatory agenda Tuesday before a House panel that has grown hostile to his plans under Republican leadership of the committee. “The SEC is the cop on the beat watching out for your constituents,” Mr. Gensler said in prepared remarks for the hearing before the House Financial Services Committee. Among other initiatives, Mr. Gensler has moved to mandate climate-change disclosures from public companies, boost regulation of private equity and hedge funds, overhaul the way stock trading works, and apply SEC rules to cryptocurrency-trading platforms.