BERLIN (Reuters) - The three candidates competing to succeed German Chancellor Angela Merkel as leader of the Christian Democrats (CDU) agreed on Thursday to revive their party’s fortunes by cutting taxes and reducing Germany’s dependence on the United States for defense.

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In a strikingly good-humored three-hour debate in the northern city of Luebeck, the first of eight meetings with party grass roots across Germany before a leadership vote on Dec. 7, the rivals barely clashed on broad policy.

While there were different nuances on details, the three agreed to work to improve the integration of migrants, focus more on affordable housing, cut subsidies to poorer eastern states and further Merkel’s digitalization drive.

The race for leader of the Christian Democratic Union party has shaped up as a dual between Merkel protege Annegret Kramp-Karrenbauer, widely seen as the continuity option, and Friedrich Merz, a millionaire who describes himself as “a free-trade man”.

Merkel has said she will remain chancellor atop a ‘grand coalition’ with the CDU’s Bavarian sister party and Social Democrats until the end of her term in 2021.

CDU General Secretary Kramp-Karrenbauer, the front-runner, won applause for saying she would continue the process of renewal, by taking into account the views of the party base.

Former Merkel rival Merz said he aimed to take the CDU back over the 40 percent mark and halve support for the far-right Alternative for Germany (AfD), currently polling at around 16 percent. The CDU is at around 26-27 percent in most surveys.

“It is our job to do this,” he said, adding the CDU had to make clear it had not forgotten voters who felt neglected after the influx of some 1.5 million migrants since 2015.

Health Minister Jens Spahn, the third candidate and an arch-critic of Merkel’s migrant policy, said CDU policy had in part led to the rise of the AfD, now represented in all of Germany’s 16 states. “We can also get rid of them,” he said.

All three candidates promised to work with each other after the leadership election and stressed their mutual respect.

“I will not criticize the others, we will only say good things about each other ... In the end, the party must be the winner,” said Merz.

An opinion poll for broadcaster ARD conducted on Monday and Tuesday showed Kramp-Karrenbauer, known as mini-Merkel, still favorite among CDU voters with 46 percent support.

The poll, released on Thursday, showed 31 percent of CDU supporters favored Friedrich Merz, returning to politics after 10 years in the private sector. Twelve percent backed Spahn.