House Majority Leader Eric Cantor on Thursday urged his Republican colleagues to stand united in the fight with President Obama and Senate Democrats over the government shutdown, reassuring lawmakers that their position is reasonable and defensible and insisting the GOP will not support a "clean" spending bill Democrats are demanding to reopen the government.

In a memo sent to all House Republicans and then released to the media, Cantor, R-Va., accused Democrats of prolonging the government shutdown by refusing to negotiate a budget bill with Republicans.

"I firmly believe their position is untenable," Cantor wrote. "Because their position is unsustainable and because we are willing to negotiate to find a reasonable resolution, I believe it is critical that we continue to engage and offer meaningful solutions for the American people."

Cantor said the Republican majority would continue to pass individual spending bills that allow only parts of the government to reopen to ease the impact of the shutdown.

Obama and Senate Democrats oppose these targeted appropriations bills, which include funding for veterans and national parks, and are refusing to do anything but support the clean continuing resolution the Senate has already approved.