GERMANY - The chances are you have never heard of Kevin Kühnert. Until a couple of months ago, few had heard of him in his native Germany. But this weekend, the 28-year-old political novice could become the man who ends the career of Angela Merkel. Mr Kühnert is leading a grassroots rebellion in the centre-left Social Democrat Party (SPD) against joining a new coalition under Mrs Merkel. A party vote on the decision this Sunday that was expected to be a formality now looks too close to call. If Mr Kühnert wins, it will plunge Germany into political chaos. Mrs Merkel will have nowhere left to look for a majority and be left with a choice between new elections or trying to form a minority government. It could be the beginning of the end for the woman who has dominated German politics for more than 12 years.