Mrs Merkel has seen her popularity tumble, with voters growing in anger over the notorious decision to open up Germany’s borders two years ago.
The German leader, from the Christian Democrat Union (CDU), remains favourite to win but faces a crucial televised debate this week.
A poll by research agency Forsa for Stern magazine indicated about half of the electorate planned to watch the debate – and about twenty per cent said the debate could swing the way they vote.
The 90-minute match-up will see rival Martin Schulz of the left-wing Social Democratic Party (SPD) try to convince Germany to leave behind their right-leaning Christian Democratic Union (CDU) chancellor.
And the former Eurocrat has been steadily building up to tomorrow night’s big debate after launching a series of personal attacks on his rival.
He told a regional newspaper yesterday: “A successful duel can create momentum.
“On Sunday we have for the first time a direct comparison. Mrs Merkel cannot avoid issues here like she always does.
“The Angela Merkel method is simply do not talk about any problems.”
Sunday night’s big showdown is the SPD’s last chance to reverse the CDU/CSU lead in the polls.
But rather than highlight his own suitability, Mr Schulz instead switched to a more aggressive approach -attacking the chancellors’ character last week as the election on September 24 grew nearer.
He tried to suggest that Mrs Merkel was in President Trump’s pocket for agreeing to raise German defence spending to 2 per cent of GDP.
And later Mr Schulz , the former European Parliament president, said Mrs Merkel was “disconnected from reality” and “aloof” – a bashing which led to the SPD leader being criticised as desperate.
He also told Die Zeit yesterday: “The CDU has a concept, and that is Angela Merkel. That is supposedly enough for you all.
“We have a concept for the future of the next generation.”