By Emma Thomasson and Andreas Rinke
BERLIN (Reuters) - Germany could stop gas flowing through the almost-complete Nord Stream 2 pipeline from Russia if Moscow breaks the terms of the arrangement or uses it to put pressure on Ukraine, conservative chancellor candidate Armin Laschet said on Saturday.
The pipeline is a source of tension with the U.S. administration, which argues that it gives too much leverage to Russian President Vladimir Putin by increasing Europe's energy dependence on Russia.
Gazprom and its Western partners have completed 95% of the pipeline to send natural gas under the Baltic Sea, bypassing Ukraine and depriving it of lucrative transit fees.
Armin Laschet, who is favourite to succeed his CDU party colleague Angela Merkel when she steps down as chancellor after September's election, said in a televised foreign policy debate that the 95%-complete pipeline should be finished.
But if Russia failed to stick to the rules, or used the pipeline against Ukraine, he said, "We can always discontinue this project, even after the pipeline is finished".
Finance Minister Olaf Scholz, chancellor candidate for the centre-left SPD, took the same line, saying: "Anything that impinges on gas transit and Ukraine's security has consequences for potential transit through the completed pipeline."
But Annalena Baerbock, the candidate for the environmentalist Greens, who are running second in opinion polls and could replace the SPD as the conservatives' junior coalition partner, repeated her opposition to the pipeline.
"Imagine a winter in Europe," she said. "We won't be able to say 'Now we don't have any more gas'. Mr Putin wants to destabilise not only Ukraine but us as Europeans."
Ukrainian President Volodymyr Zelenskiy made a recorded appeal to the candidates to guarantee his country's security and provide it with a path to membership of the European Union.
Both Laschet and Scholz said Ukraine was not the next priority for EU enlargement.
Baerbock, a foreign policy expert, also staked out tougher lines than her rivals towards China, Hungary and arms exports.
She said products from China's Xinjiang region should not be allowed into the European Union because of Beijing's treatment of Uyghurs and other ethnic minorities in the region.
"We need a dialogue but we need a tough approach," she said. "We need to be clear about values."
Laschet said it was important to keep talking to China to tackle climate change, even though it was a growing competitive threat, while Scholz warned against isolating Beijing. "We shouldn't fall into the trap of dividing up the world," he said.
Baerbock called for the European Union to cut funding to Hungary over a law that bans schools from using materials seen as promoting homosexuality. Scholz and Laschet said the EU should wait for its highest court to make a ruling.
"What is happening in Hungary is unacceptable," Laschet said. "But we shouldn't fall into the attitude of just pointing the finger."
Asked whether Germany should still sell arms to authoritarian countries in the Middle East, Baerbock said "No", while Laschet and Scholz supported continued sales.
The candidates were each asked to say what ability they appreciated in their rivals: Laschet said he liked Scholz's pragmatism and Baerbock's idealism. Baerbock described Laschet as resilient and Scholz as calm.
Scholz said Baerbock was very committed, and that he liked Laschet's jovial Rhineland demeanour.
(Additional reporting by Andreas Rinke; Editing by Kevin Liffey)