German Chancellor
Its coalition partner, the social democratic SPD, has gained 20%, BBC reports.
Meanwhile, the AfD, a nationalist, anti-Islam party, was on track to win 13.5%, emerging as Germany's third-strongest party.
AfD's performance, better than what opinion poll had forecast, means that the far-right party will have a seat at the Bundestag for the first time.
Reports say Merkel will now have to form a coalition government, a process that could take months.