Nikki Haley Reuters US Ambassador to the UN Nikki Haley is urging countries at the United Nations to back a US-drafted resolution condemning the Hamas terrorist organization, warning in a letter that the United States takes the vote "very seriously."

The UN General Assembly is scheduled to vote Thursday on the draft resolution that would condemn Hamas for firing rockets into Israel and demand that it ends the violence.

All 28 EU countries agreed to support the measure after the United States included a mention of relevant UN resolutions in the text that does not, however, refer to "the two-state solution."

In a letter sent to UN diplomatic missions and quoted by AFP , Haley warned that there could be attempts by some countries to introduce amendments to the text and urged ambassadors to vote against any such proposed changes.

"The United States takes the outcome of this vote very seriously," wrote Haley in the letter, which is dated Monday.

"The resolution has been carefully-crafted to address a specific problem, and it reflects consultations with many stakeholders to ensure balance,” she added.

"That is why we are asking that you not only vote in favor of the resolution but that you also vote against any amendments or other efforts to undermine adoption of the text," wrote Haley.

On Monday, Haley referred to the vote on Twitter, writing, “Countries must now ask themselves: are they for or against Hamas’ violence? The choice is clear for the US - we hope it will be for the rest of the UN as well.”

Arab countries are expected to put forward amendments to the resolution and push for a ruling at the General Assembly that would specify that the measure must be adopted by a two-thirds majority, instead of a simple majority, noted AFP .

Hamas has been trying to convince the UN to vote down the measure. Last week, Hamas leader Ismail Haniyeh wrote directly to UN General Assembly president Maria Fernanda Spinosa, in response to the US and Israel's efforts against Hamas in the UN.

This week, Hamas received surprising support from its longtime rival Fatah, which is headed by Palestinian Authority chairman Mahmoud Abbas.

Abbas Zaki, a member of the Fatah Central Committee, condemned the American resolution and described it as a "clear racist decision".

On Monday, US special envoy Jason Greenblatt slammed the PA for defending Hamas, calling its actions “beyond absurd”.

Tags: Hamas , UN General Assembly , nikki haley