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Oil, Greece turmoil set to weigh on Wall Street

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U.S. stock index futures signaled a lower open on Tuesday, as oil prices continued to weaken and Greece remains in focus after the country's parliament failed to elect a president.

"While European markets continue to react to yesterday's Greek news, I think the biggest market risk going forward for the rest of us is not what happens politically or economically in Greece...but if the goings on there instead impacts what the (European Central Bank) wants to do going forward," Peter Boockvar, chief market analyst at The Lindsey Group, said in a note.

Brent oil extended losses into a fourth session, with prices hitting a 5-½-year low below $57 per barrel, despite ongoing output disruptions in Libya.

Read More Why Greece is not the risk it once was The Case-Shiller house price index for October showed that U.S. single-family home prices' rate of increase continued to decelerate in October since the stronger-than-expected rise seen in the previous month. The December reading of the Conference Board's consumer confidence due at 10:00 AM ET. No major earnings are set to be reported.

European shares remained under pressure on Tuesday, as Greece fears continued to weigh. The Greek parliament, for a third time, failed to elect a new president on Monday, meaning a general election has been called for January 25. There are worries that far-left anti-austerity party Syriza could win, with polls showing that the party has a narrow lead, according to Reuters. Athens main stock exchange (Athens Stock Exchange: EXAE-GR), which ended almost 4 percent lower on Monday, traded around 0.88 percent lower. In other news, bodies and debris have been found in the search for the AirAsia flight QZ8501, which went missing early on Sunday, according to various media reports.

Read More Early movers: CSC, CVEO, BP, ARCP, TM & more Indonesian officials confirmed that the debris, which was located close to the last captured radar message from the jet, were from the plane. The country's search and rescue agency confirmed to NBC that at least six bodies had been found, three of which had been recovered.