BERLIN, Aug 20 (Reuters) - A member of Angela Merkel"s conservatives dismissed suggestions on Friday that they should drop their candidate to succeed her as German leader, despite his souring popularity ratings that could cost them an election they had looked certain to win. Less than six weeks before the Sept. 26 vote, support for Merkel"s Christian Democrats (CDU) and their Bavarian sister party, the Christian Social Union (CSU), has fallen to 23%, some 10 points lower from the last election and only 2 points ahead of the centre-left Social Democrats (SPD). Some conservatives have blamed the drop in support on the bloc"s candidate for chancellor, CDU chairman Armin Laschet, whose ratings have tumbled since he was caught on camera laughing during a visit last month to a town hit by floods. Health Minister Jens Spahn, a close Laschet ally, ruled out suggestions that replacing Laschet with a more popular candidate, such as Bavarian premier Markus Soeder, was the only way to secure a comfortable victory. Spahn told the Mannheimer Morgen newspaper there was no plan to replace Laschet with Soeder, adding "and you will get the same answer if you asked Soeder." Merkel, in power since 2015, will step down after the election leaving a conservative bloc weakened by divisions over the direction of the party. Editing by Catherine Evans Our Standards: The Thomson Reuters Trust Principles.