BERLIN (Reuters) - Chastened by their worst result since 1949 in September’s national election, Chancellor Angela Merkel’s conservatives are hoping for victory in a regional vote on Sunday to strengthen their hand in thorny three-way coalition talks in Berlin.

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While victory in the Lower Saxony region might strengthen Merkel’s position within her party, a conservative failure to emerge as the strongest party could prompt talk of weakening authority and possible eventual succession, said Berlin-based political expert Gero Neugebauer.

Lower Saxony, an agricultural heartland and Germany’s second biggest region, offers Merkel’s Christian Democrats (CDU) the prospect of a morale boost as they seek to cobble together an unprecedented “Jamaica” national coalition with the liberal Free Democrats (FDP) and Greens.

The road to such an alliance, named after the Caribbean nation as the parties’ colors match those of its flag, is littered with disputes on everything from migrants to tax and the environment. It would be the clunky coalition’s federal debut if talks, due to start next week, prove a success.

Carsten Nickel, deputy research director at Teneo Intelligence, said Sunday’s election - which polls show is set to be a neck-and-neck contest between the CDU and the rival Social Democrats (SPD) - would determine momentum going into national coalition negotiations.

The election in the northern state, home to carmaker Volkswagen VOWG_p.DE, was called after a lawmaker in the Greens party - junior coalition partner to the SPD there - defected to the CDU, robbing the ruling alliance of its one-seat majority.

“If Merkel managed to steal that state from the SPD, it would probably be a little bit of a boost,” he said. “It would probably be slightly easier for her to argue internally for the required compromise and for striking the deals and so on that will be required over the next couple of weeks.”

SPD EDGES AHEAD

However, a new poll for broadcaster ZDP released late on Thursday showed the SPD with 34.5 percent, closely followed by the CDU with 33 percent. The Greens and FDP both had 9 percent while the anti-immigrant Alternative for Germany (AfD) was on track to get 7 percent and move into Lower Saxony’s state assembly for the first time. The Left party got 5 percent.

About 29 percent of voters were still undecided about which party to support or whether to vote at all, it showed.

The CDU has dropped far below the 12-point lead it had over the SPD in August at the start of a campaign that has centered on regional issues such as education, as well as an influx of migrants to Germany over the last two years.

The latest poll means the SPD and Greens would not have enough support to govern again, even if they joined forces with the Left party. That leaves a coalition of the SPD and conservatives, a coalition of the SPD, Greens and FDP, or the Jamaica coalition being pursued on a national level.

Merkel’s CDU and their Bavarian sister party (CSU) removed a major stumbling block to those coalition talks on Sunday by ending a dispute over migrant policy with an agreement to limit the number of migrants coming to Germany.

Merkel’s conservative bloc won 33 percent in September’s national election, losing 8.5 points compared with 2013, as voters upset with Merkel’s 2015 decision to open the borders to more than a million migrants abandoned the party. The result effectively brought an end to the existing national coalition with the SPD, who also performed badly.