By Alexandra Hudson and Erik Kirschbaum
MAGDEBURG/BERLIN (Reuters) - Angela Merkel warned cheering supporters in the eastern city of Magdeburg on Tuesday not to split their vote to save her Free Democratic (FDP) coalition partners, in a sign of raw nerves ahead of a tightly-contested German election on Sunday.
"We are separate parties with different policies and we have no votes to give away," she told a rally in an old market square packed with supporters waving "Angie" posters and eating ice in her party's orange campaign colors.
The chancellor is worried her supporters will split their two votes - one for a constituency member of parliament, one for a party list - between her Christian Democrats (CDU) and the FDP as they have in previous votes with her tacit encouragement.
If the CDU and FDP do not get enough votes to continue their center-right coalition, Merkel will have to revive the 'grand coalition' with the Social Democrats (SPD) that she led from 2005-2009. Neither partnership is without difficulties.
"Merkel has done well in the last years. To be honest it would be good to see her rule alone, but realistically I'd much prefer it was with the FDP than the SPD," said Markus Wylega, a 22-year-old student. "She's a strong lady - no bad thing."
Free-marketeering and socially libertarian, the small FDP has served in most German governments since 1949, at times with such influence that it was dubbed the tail that wags the dog.
But its survival in parliament in Berlin is in doubt after it crashed out of Bavaria's assembly in an election last Sunday, falling well short of the 5 percent required to win seats.
Far from offering their allies a helping hand, Merkel's conservatives have stepped up their campaign for both votes, haunted by a shock defeat in a Lower Saxony state election in January, when the FDP successfully siphoned off CDU support.
In past polls, a tactical second vote for the FDP has helped it clear the 5 percent hurdle and keep a center-right coalition.
Now the CDU is trying to stamp out the practice, not least because it faces another challenge from an anti-euro party, the Alliance for Germany, which could also grab conservative votes.
"I've never seen coalition partners fight each other for the same voters like this," said Hans Vorlaender, a political scientist at Dresden University. "It's an act of desperation for the FDP to beg so openly for CDU votes. The CDU got burned before about vote splitting and has learned its lesson."
Hovering around 5 percent in opinion polls, the liberals made a renewed pitch for second votes this week by saying a vote for the FDP was a vote to keep Merkel. Her tacit support helped the FDP to a record 14.9 percent in the 2009 election.
"You get a dual effect by giving the FDP your second vote," said top FDP candidate Rainer Bruederle. "The first vote is for Mrs Merkel and the second for a center-right government."
Merkel hit back in her Magdeburg rally, telling supporters: "When it comes to the second vote, it may not be my name on your ballot paper, but that is the vote which will help me to stay chancellor. So I ask you also for this vote. You only get Merkel with the CDU."
Opinion polls point to a 44-44 percent draw between the center-right and center-left. Merkel's conservatives are polling around 39 percent with the FDP on 5. The SPD and their Greens allies are on 34 percent and the hardline Left party, regarded as too radical to join any coalition, is on 10 percent.
Despite uncertainty over what kind of alliance she may lead, Merkel appeared confident in Magdeburg, celebrating Germany's low unemployment, social safety-nets and its secure future.
"Take someone by the hand on Sunday and tell them 'let's vote and do something good for Germany, we live in a wonderful country'," she said in the reassuring tone that earns her the nickname "Mutti" (mummy), printed on banners next to a heart.
"Such mush," shouted one disgruntled 77-year-old woman who would not give her name. "Merkel has all these warm, reassuring phrases but it's just talk. We see her smiling down on us from all those election posters but there is nothing to her."
(Editing by Stephen Brown and Paul Taylor)