Why did the Government attach the Tax Credit Extension to the Unemployment Benefits Bill???

This is so frustrating to me.  The senate and the house have huge bipartisan support to extend the home buyers credit for sellers that are in a short sale situation.  There is not overwhelming support to extend the unemployment benefits though.  So why did they tie the two together?  Why can't they separate the bills and have a stand alone vote with overwhelming support of the extension?  I think they are trying to force the Republicans into voting on the unemployment bill by addingit to the very popular home buyer extension.

Here's a current article from the AP: http://www.google.com/hostednews/ap/article/ALeqM5hLKyB9H7lUpiALFVlU7RRJa9-EfwD9GLNM104