Washington (CNN) -- President Obama's plan to train and arm Syrian rebels in their battle against ISIS fighters faces deep skepticism from a large number of Democratic senators who will vote Thursday whether to approve the escalation of U.S. involvement in the deadly conflict. While Senate leaders are confident the measure will pass, misgivings raised by so many senators from the President's party speak to the difficulty the administration is having gaining traction for its ISIS policy. It also suggests an upcoming debate in November over whether to OK broader military action against ISIS could be contentious. House approves plan to assist Syrian rebels
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House votes to approve arming and training Syrian rebels
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Democratic-led Senate votes on the measure Thursday
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Many Democrats are skeptical and believe the effort could lead to a slippery slope
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Measure will be tucked inside a government spending bill
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