By Claudia Doerries and Erik Kirschbaum
BERLIN (Reuters) - The leader of Germany's Free Democrats (FDP) said on Saturday his party was confident of returning to parliament in September and eager to put its pro-business stamp on the next government - whether with Angela Merkel's conservatives or the Social Democrats.
In an interview with Reuters at a congress in Berlin to launch the centrist party's campaign for the Sept. 24 national election, FDP chairman Christian Lindner said its primary goal was to clear the 5 percent voter threshold needed to enter parliament again.
The FDP, which dropped out of the federal legislature in 2013 when its share of the vote fell to 4.8 percent, has been kingmaker to 17 of the country's 25 post-war governments on both the right and left.
Lindner, who has helped the FDP rally back to around 6 percent in opinion polls, said the party would not pledge itself as a coalition partner before the election -- after it aligned itself to the Chancellor's Christian Democrats in 2013 only to crash out of parliament.
"We're independent but we're not going to take the first (partner) that comes along," Lindner told Reuters.
That strategy might frighten away some conservatives from casting one of their two federal election ballots for the FDP, but could open the door to left-leaning voters who want to see the FDP join forces with the center-left Social Democrats (SPD).
Germans cast two ballots - one for the party and one for the candidate in their district. Some voters split their votes in a way to help both parties when they have pledged to a coalition.
"We're reaching out to people who cherish freedoms and want to take responsibility for themselves - regardless of their walk of life, age, sex or income," Lindner said.
He estimated 60 to 70 percent of Germans counted on the state to care for them and were thus unlikely to vote for the FDP.
"We're appealing to the rest in Germany who want to take their fate into their own hands," he added.
"We don't have a set target for September but we want more than five percent and there's no upper limit.".
The FDP has been hovering between 5 and 7 percent in national polls over the last year after plunging to 2-3 percent in 2013. It has cleared the 5 percent threshold in nine of the last 16 state elections and is projected to win 12 percent in Lindner's home state of North Rhine-Westphalia on May 14.
Other FDP leaders told delegates to the party congress that they would only join a coalition with either major party - the Christian Democrats or the SPD - in exchange for a commitment to the reform vision the FDP has for Germany.
Analysts believe the FDP could play a pivotal role after the election, either helping Merkel retain power in a three-way alliance together with the Greens, or again combine with the Greens in an SPD-led coalition.
(Additional reporting by Thorsten Severin, writing by Erik Kirschbaum; editing by John Stonestreet)