Former Massachusetts Gov. Mitt Romney raised the stakes in his effort to convince voters he is Israel’s best friend among the GOP presidential field, arguing in an op-ed with former Sen. Norm Coleman (R-Minn.) that President Obama not only should oppose a Palestinian bid for statehood but also aggressively persuade other nations to do the same.

Romney and Coleman argued in the conservative National Review that a planned attempt by Palestinians to seek recognition from the United Nations is part of a “vicious campaign to delegitimize the State of Israel” and cannot lead to peace.

“Although the Obama administration has demonstrated a congenital inability to get things right, a proper U.S. policy would be to launch an all-out diplomatic campaign to discourage the vote,” the two wrote.

Coleman, who is Jewish, has endorsed Romney and is advising his presidential campaign.

Romney has repeatedly accused Obama of throwing Israel “under the bus” by calling for negotiations with Palestinians to use 1967 borders as a starting point. He said Obama’s calls for Israel to stop building settlements in the West Bank has emboldened Palestinians to demand more concessions and made it easier for Syrian dictator Bashar al Assad to blame the Jewish state for his troubles.

“A first lesson is that the United States needs a president who will not be a fair-weather friend of Israel,” Coleman and Romney wrote. “President Obama has shamefully broken with longstanding American traditions in distancing the United States from Israel.”

Obama has pledged to veto the Palestinian statehood bid in the U.N. Security Council and called for a return to Israel’s preferred method of negotiations, but has nonetheless taken flack from Republicans for not unquestioningly supporting the United States’ strongest ally in the Middle East.