* Escalation of rhetoric before September election
Chancellor Angela Merkel told voters they could not trust the opposition Social Democrats as they had a track record of breaking promises to grab power with the help of the ostracised far left, in an escalation of rhetoric before elections.
Merkel's conservatives hold a 16-point lead over the Social Democrats (SPD) in polls, but she fears the opposition might still be able to win if it forms a coalition with the Left Party - a movement with its roots in former East Germany's Communists.
The SPD and their allies the Greens have ruled out a deal with the "Linke" or Left Party - a group blamed by many for cementing the division of the country until the fall of the Berlin Wall.
But Merkel ripped into the SPD's record with unusual clarity on Sunday, saying they had even broken promises on when they would pick their chancellor candidate.
"The SPD denies it (that they will join forces with the Left) but I've got to tell people you can't trust someone who can't even stick to agreements on when to pick their chancellor candidate," Merkel told ZDF television. The SPD nominated Peer Steinbrueck in September, four months ahead of schedule.
The main parties have kept their distance from the Left Party on the national level but it remains popular in the east and has 8 percent support in polls.
Merkel reminded voters the SPD had done an about-face after two state elections in western Germany in recent years, first saying they would not rely on the Left party but then doing so in Hesse and North Rhine-Westphalia.
"I don't even have to mention the names of Frau (Hannelore) Kraft and Frau (Andrea) Ypsilanti," Merkel added, referring to two SPD regional leaders who changed their minds after elections in 2008 and 2010 and did deals with the Left Party.
"I'm certain this election is going to be end up being very, very close," Merkel added.
An opinion poll published on Friday showed Merkel's centre-right coalition was in a 46-46 dead heat against the three leftist opposition parties.
"It would be extremely negligent for anyone to think I'll still be chancellor no matter what happens. It could end up being the case that on Monday after the election we'll wake up in a country with SPD-Greens and the Left party in charge."
Merkel, seeking a third term in the Sept. 22 election, also warned her supporters against complacency in a speech on Saturday, voicing similar fears that three leftist parties could unexpectedly join forces to oust her centre-right coalition.