Tim Alberta makes a good point in the National Journal today:

[A]ny comprehensive measure agreed to in the House will be substantially to the right of the Senate bill. This would reflect the conservative membership of the House majority, they argue. But if such a bill passed the lower chamber, it could threaten to shatter the delicate coalition assembled by Senate negotiators, who won the support of both labor and business groups with an emphasis on compromise and middle ground. (my emphasis)