Charles Grassley had hoped the Senate finance committee, which he chairs, would be working this month on the finer points of a Social Security reform bill. But when Republicans on the committee meet today in what has become a weekly private session, they will still be addressing broad questions about how to improve the long-term solvency of the system.

That slow progress is the result of basic disagreements over how to reshape the popular programme, according to senators involved in the talks, and it puts Republicans in an uncomfortable position. While they have complained for months that Democrats were not co-operating on Social Security, they are beginning to acknowledge another problem: divisions in their own ranks.