From the story here:
Merkel was weakened after an election in September as voters angry with her decision in 2015 to open Germany's borders to more than a million asylum seekers punished her conservatives by voting for the Alternative for Germany (AfD) far-right party.
There is little appetite for a second vote, especially as the main parties fear that the populist AfD would win more than the almost 13 percent of votes it secured in September.