By Thomas Escritt
BERLIN (Reuters) - Chancellor Angela Merkel's conservatives and the liberal Free Democrats are popular enough together to form a government, a new poll shows, raising the prospect of a return to the pro-business tandem that ruled Germany for much of the post-war era.
The resurgent Free Democrats (FDP) are back in third place in a poll after being all but wiped out in the 2013 general election, but its young leader has warned against complacency, saying the party was no shoo-in at the Sept. 24 vote.
The FDP was on 9 percent in Tuesday's Forsa poll, comfortably above the 5 percent threshold for entering parliament that it missed in 2013, when voters deserted them after four years in coalition with Merkel's conservatives. Her conservatives are now in a sometimes awkward "grand coalition" with the Social Democrats.
The FDP served as junior coalition partner to the Christian Democrats (CDU) and their Bavarian Christian Social Union (CSU)sister party for almost half of Germany's post-World War Two history. A resurrection of the FDP role as kingmaker would be a coup for its young leader Christian Lindner.
On Tuesday, the FDP opened coalition talks with the CDU in the state of North Rhine-Westphalia after winning almost 13 percent of the vote there, its liberals' best-ever result in Germany's most populous state.
But, wary of being typecast as the CDU's partner, Lindner has been careful to highlight his differences with Merkel's party, praising some of the plans rolled out by Social Democratic (SPD) leader Martin Schulz.
"I'm glad Mr Schulz supports our push for better education," Lindner, 38, told Die Welt newspaper on Monday. "We have something in common with the CDU on economic policy... But we are very critical of Mrs Merkel on refugee policy and the euro."
The FDP wants tax cuts and increased infrastructure investment. Abroad, it wants the European Union to abandon accession talks with an increasingly authoritarian Turkey - a move Merkel opposes because of President Recep Tayyip Erdogan's role in helping Europe deal with the refugee crisis.
Unlike Emmanuel Macron, a centrist who romped to victory in the French presidential election with a very pro-EU message, the FDP has been skeptical about European integration and echoes CDU Finance Minister Wolfgang Schaeuble's tough line on financial bailouts for Greece.
For Macron, a continuation of Germany's current pro-European coalition of the CDU-CSU and center-left SPD would likely make for a more comfortable partnership.
But Lindner was cautious about booking victory too early. "The FDP comeback on the federal level is now more likely, but it's not certain," he said. "We live in turbulent times."
The Free Democrats were also in a national ruling coalition with the Social Democrats from 1969 to 1982.
(Reporting by Thomas Escritt; editing by Mark Heinrich)