(NBC NEWS) After freezing temperatures and travel woes forced a one-day delay, the Senate is scheduled to take a key first vote Tuesday on a temporary extension of unemployment benefits to 1.3 million jobless Americans.

But backers still appear to be just short of enough support to move the bill forward, as Democrats scramble to win over the handful of Republicans needed to clear the 60-vote threshold to advance it.

The vote was originally scheduled for Monday evening but abruptly postponed after Republicans noted that more than a dozen senators had been unable to travel back to the Capitol due to the weather.

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