From Fitch Credit Ratings:
In Fitch's opinion, the debt ceiling is an ineffective and potentially dangerous mechanism for enforcing fiscal discipline. It does not prevent tax and spending decisions that will incur debt issuance in excess of the ceiling while the sanction of not raising the ceiling risks a sovereign default and renders such a threat incredible.
The statutory limitation on federal debt is a long-standing feature of the U.S. fiscal framework and applies to nearly all Treasury debt, whether held by the public or in government accounts. Protracted debate prior to increasing the debt ceiling is not an exceptional event, but against the backdrop of unprecedentedly large peacetime budget deficits and outstanding debt, any delay in raising the limit would pose ever increasing risks to the ability of the federal government to honour its obligations in a timely fashion. The last time Congress approved an increase in the debt ceiling in August 2011, the federal government came perilously close to being in a situation where, in the words of the Treasury Secretary, it would be unable "to meet our commitments securely"...
In the absence of an agreed and credible medium-term deficit reduction plan that would be consistent with sustaining the economic recovery and restoring confidence in the long-run sustainability of U.S. public finances, the current Negative Outlook on the 'AAA' rating is likely to be resolved with a downgrade later this year even if another debt ceiling crisis is averted.
Fitch Ratings - Dedicated to providing value beyond the rating
It has now been two weeks since the fiscal cliff issue was resolved. Neither the Congress nor the President have opened negotiations on a fiscal consolidation program, much less offered any concrete fiscal consolidation plans. As a substitute for fiscal responsiblity, some Members of the House appear willing to drive the nation into partial default. However, some responsible political leaders are starting to push back and are rejecting efforts to play politics with the debt ceiling.