BERLIN, May 6 (Reuters) - Germany’s parliament will hold a second vote on Tuesday on backing Friedrich Merz as chancellor after the veteran conservative failed to secure enough support in a first round, throwing politics in Europe’s largest economy into disarray.

The Bundestag lower house is set to reconvene around 1515 local (1315 GMT) to hold a second vote on Merz, said Jens Spahn, parliamentary group leader of the conservative CDU/CSU bloc.

“All of Europe — perhaps even the whole world — is watching this second round of voting,” Spahn said. “I appeal to everyone to be aware of this special responsibility.”

Merz, 69, who led his conservatives to a federal election victory in February and has signed a coalition deal with the centre-left Social Democrats (SPD), won just 310 votes in the Bundestag, six short of an absolute majority. At least 18 coalition lawmakers failed to back him.