FRANKFURT/BERLIN- The future of Germany's ruling coalition looked shaky after the election of new leaders of the Social Democrats (SPD) who are demanding a shift in policies, but several senior conservatives on Sunday ruled out talks to renegotiate a governing agreement.

Two fierce critics of the coalition with Chancellor Angela Merkel's conservatives - Norbert Walter-Borjans and Saskia Esken - won a vote for leadership of Social Democrats on Saturday.

They want to renegotiate the coalition deal to focus more on social justice, investment and climate policies. 

"Of course nothing will be renegotiated now. That's quite clear," Armin Laschet, the Christian Democrat (CDU) premier of North Rhine-Westphalia, Germany's most populous state, told broadcaster Deutschlandfunk in an interview.

Asked whether there was movement on the issues that the new SPD leadership wants to change in a new agreement, Laschet said: "There is no such thing."

Walter-Borjans and Esken, who ran on a joint ticket, beat Finance Minister Olaf Scholz and Klara Geywitz, who said they would support their rivals. SPD delegates are set to approve the leadership - elected via a party ballot that ended Saturday - at a party conference starting on Dec. 6. They will also vote on the coalition.

Laschet said new demands were a problem of the SPD duo, not of the Christian Democrats, saying holding an election would be irresponsible in the current environment.

Conservative Agriculture Minister Julia Kloeckner, too, said there was no chance of renegotiations, adding the CDU would stick to the promises it made.

"A one-sided renegotiation, just because SPD leadership has changed, will not be doable with the (Christian Democratic) Union," she told Funke Mediengruppe.

Merkel, 65, has been in power since 2005 and has said she will not seek re-election at the next national election, due in 2021. The CDU is trying to boost its image and appeal to hold its position as the leading governing party after she goes.

(Reporting by Christoph Steitz and Andreas Rinke Editing by Frances Kerry) ((christoph.steitz@thomsonreuters.com; +49 69 7565 1269; Reuters Messaging: christoph.steitz.thomsonreuters.com@reuters.net))