US lawmakers from both the Democrat and Republican parties stepped up pressure on President Barack Obama to level tough new economic sanctions on Iran in the event that Teheran fails to freeze its nuclear program by late 2009, AFP reported on Monday. Republican Senators Jon Kyl and John McCain, Independent Senator Joseph Lieberman, and Democratic Senator Evan Bayh urged the president to prepare sanctions targeting the Central Bank of Iran in the case of a diplomatic stalemate. The four lawmakers introduced a bill calling on the president to act if Iran does not accept his offer of direct talks before a late September summit of the Group of 20 or fails to freeze uranium enrichment and reprocessing activities 60 days after that.