SCENARIOS - Foreign policy in the next German government

BERLIN (Reuters) - German Chancellor Angela Merkel is seeking re-election in a federal vote on September 27, and polls give her conservatives a sizable lead over their coalition partners and traditional rivals, the Social Democrats (SPD).

Merkel hopes to form a coalition with the business friendly Free Democrats (FDP), and the latest surveys give her enough support for such a centre-right alliance.

However, other ruling partnerships are possible, including a second consecutive "grand coalition," grouping Merkel's conservatives -- her Christian Democrats (CDU) and the Bavarian Christian Social Union (CSU) -- and the SPD.

Below are the most likely coalition scenarios and how they would probably affect German foreign policy:

CENTRE-RIGHT ALLIANCE (CDU/CSU and FDP)

EU ENLARGEMENT - The CDU/CSU believes the European Union should offer Turkey a "privileged partnership" that stops short of full membership in the bloc and is likely to push more aggressively on this issue if it seals a coalition with the FDP. The FDP does not oppose Turkey joining the bloc but cites "major deficits" in Ankara's efforts to meet EU criteria.

AFGHANISTAN - Both the CDU/CSU and FDP support the German mission in Afghanistan, but the FDP has pressed during the election campaign for a debate on when troops can return home. The coalition would likely resist calls from the United States and other NATO partners for Germany to increase its presence.

IRAN - All the parties support diplomacy in dealing with Iran's nuclear programme and this coalition would continue to participate in the P5+1 process and support U.S. President Barack Obama's offer of direct talks with Tehran.

RUSSIA - This coalition could adopt a more critical line with Russia on human rights and Kremlin interference in corporate affairs, but would continue a pragmatic partnership on energy and economic issues.

UN REFORM - The FDP favours a single European seat on the United Nations Security Council and sees a German seat, supported by the CDU/CSU, as a second-best solution.

GRAND COALITION (CDU/CSU and SPD)

EU ENLARGEMENT - As was the case for the past four years, the CDU/CSU would have to agree not to actively block Turkey's EU bid because the SPD supports it, but it would continue to publicly state its preference for a "privileged partnership."

AFGHANISTAN - Although the parties support Germany's troop presence, the left-wing of the SPD which is sceptical of the Afghanistan mission could gain a bigger voice within the party and demand talks on a timeline for pulling out.

IRAN - All the parties support diplomacy in dealing with Iran's nuclear programme and this coalition would continue to participate in the P5+1 process and support U.S. President Barack Obama's offer of direct talks with Tehran.

RUSSIA - Expect a steady course with the CDU/CSU talking out on human rights abuses, but all coalition parties favouring a pragmatic partnership on energy and economic issues.

OTHER CONSTELLATIONS

The three other coalitions that are considered possible after the German election are a CDU/CSU partnership with the Greens, an SPD coalition with the FDP and Greens and, least likely, a CDU/CSU government with the FDP and Greens. None of these constellations would lead to significant changes in German foreign policy, but the presence of the Greens in all three scenarios suggests a more critical view of foreign combat missions like Afghanistan and of human rights abuses in countries like Russia and China.

(Writing by Noah Barkin; Editing by Charles Dick)