By Hans-Edzard Busemann
BERLIN (Reuters) - Leading members of Chancellor Angela Merkel's conservatives expressed optimism on Thursday that coalition talks with the Social Democrats (SPD) would be wrapped up on Sunday, signaling an end to four months of political limbo in Germany.
To guarantee her a fourth term, Merkel needs the SPD to agree to a re-run of the "grand coalition" that has ruled Europe's biggest economy since 2013.
Investors fear the protraction of the talks is delaying reforms at home and in the European Union, after an earlier attempt at a coalition with smaller parties collapsed in November.
"At this point, I still expect (completion) by Sunday," Horst Seehofer, the combative conservative leader of Bavaria, told reporters before a meeting of Germany's 16 federal state chiefs with Merkel.
Armin Laschet, conservative premier of the state of North Rhine-Westphalia, said Monday and Tuesday were "reserve days" which he hoped would not be needed. "I hope we'll get it done by (the end of) the weekend," he said.
Working groups will resume later on Thursday with the aim of finalizing agreements on topics including pensions. Other thorny issues include health reform, labor law and European policy.
Seehofer insisted that a new coalition must stick to plans limiting additional government spending to 46 billion euros ($57 billion) through to 2021, the basis of a blueprint agreed in exploratory talks last month.
The parties have agreed on climate goals, pension contributions and family reunions for migrants.
On Thursday, Germany's lower house of parliament voted to extend the rules to stop reunions of migrants until the end of July, agreed by would-be coalition partners just two days ago. The existing suspension, introduced in 2016, had been due to expire.
Merkel's Bavarian allies have dug in their heels against more generous migrant policies demanded by the SPD.
A row erupted between the two sides after Tuesday's compromise on reunions, with both trying to paint it as a victory.
But leading Social Democrat Manuela Schwesig struck a cautious note on migrant policy.
"I would not speak of a success on family reunions, that would be totally exaggerated," she told ZDF television, adding, however, that a resumption in reunions represented progress.
The party's roughly 440,000 members could yet sink any deal as they have the final say in a ballot.
The JUSOS youth wing of the SPD, along with other leftist members, are deeply opposed to rejoining a coalition under Merkel, fearing it will decimate their support.
(Writing by Madeline Chambers; editing by Andrew Roche)