BERLIN (AFP) - German Chancellor Angela Merkel and her rivals made a last-ditch scrap for votes Friday ahead of an election to choose the coalition that must pull Europes top economy out of its worst post-war slump. Barring a huge election day surprise Sunday, the popular Merkel-Forbes magazines worlds most powerful woman for the past four years-was expected to win a second term at the helm of the worlds number-two exporter. A new poll published late Friday showed the race could yet be a real cliffhanger, with Merkels conservative Christian Democrats (CDU) leaking support and her preferred coalition looking ever less certain to win power. The survey, by the Forsa institute for Stern magazine and RTL television, put the CDU on 33 percent and its preferred partner, the Free Democrats (FDP), on 14 percent-leaving its coalition hopes on a knife-edge. Merkels traditional rivals, the centre-left Social Democrats (SPD), are polling at 25 percent, the far-left Linke party 12 percent and the Greens 10 percent. Moreover, 26 percent are still undecided, according to Forsa, which surveyed voters September 21-24, meaning there is still plenty to play for as the race heads into the final straight. SPD candidate Frank-Walter Steinmeier hopes to galvanise supporters at a rally at Berlins Brandenburg Gate later Friday while Merkel, currently in Pittsburgh for the G20 meeting, holds her final rally in Berlin Saturday. The CDU is getting more and more nervous, said Steinmeier late Thursday in Trier. Meanwhile the conservatives launched a 72-hour final campaign. This election is going to be decided in the final metres, CDU general secretary Ronald Pofalla said. The number of undecided voters is high ... we are going to use these last important hours and mobilise all our strength. With Germany facing its worst economic downturn since the war, a survey by business daily Handelsblatt showed that unemployment and the recession were voters top concerns. Economic policy is one of the few areas the two main parties have clearly defined differences, with the CDU calling for tax cuts across the board and the SPD wanting to raise the tax rate for high-income earners. Moreover, the SPD wants to introduce a nationwide minimum wage of around 7.50 euros (11 dollars), which the CDU rejects. Awaiting the elections winner are several economic headaches, including a record debt mountain, a likely rise in unemployment and stagnating consumption. Exit poll results, expected at 1600 GMT Sunday, could well prompt hours of nail-biting as party leaders haggle over possible coalitions. Another survey by the Emnid polling agency showed that Merkel remains popular among voters but that more Germans would on balance prefer another four years of the loveless grand coalition between the CDU and the SPD. According to the poll, 49 percent of voters would prefer a grand coalition, compared to 38 percent sharing Merkels preference for a combination of CDU and FDP. Nearly seven out of 10 voters rated Merkels performance as good or very good, the survey indicated. The person who wins will be the person who manages to transform the number of undecideds into three or four percentage points, polling expert Ulrich Eith told the Financial Times Deutschland. The election is set to be an extremely close contest between the left-wing and right-wing blocs, and there is the potential for a number of twists, Grace Annan from IHS Global Insight said in a research note. Voters will have no excuse not to go to the polls Sunday as the weather is set to be sunny and dry. If the turn-out on Sunday does not meet expectations, its not the weathers fault, said the weather service in a statement.