The allies of Congress (I) have all given letters of support to Sonia Gandhi. However the important allies are refusing to be part of the government, and have said they will support the government from outside. These parties include all the left parties comprising close to 60 MPs, DMK with 15 MPs and NCP with 9 MPs. It is unclear what RJD's views are in this regard. Only PMK with 6 MPs have openly agreed to be part of the government. SP's Amar Singh has exchanged acrimonious exchanges with a few Congress (I) leaders and Congress (I) has not explicitely sought SP's support, nor has it tried to work out a deal with SP.
This is not good for the stability of the government. The left parties will get the opportunity to constantly threaten the government on several key economic issues and would not offer any alternate solution. Since they are not part of the government, they have no responsibilities - particularly to balance the budget or at least keep the fiscal deficit within a reasonable limit. Nor would they be interested in understanding the difficulties the government will be facing in managing trade negotiations with WTO countries, various other commerce ministry related issues, fiscal policy, policy related to VAT, policies related to regulations on broadcasting (say CAS), foreign direct investment and so on. I am not even touching disinvestment.
Observers may point to Chandrababu Naidu doing the same for the previous government. However the situation is quite different here. The NDA coalition that took part in the ministry had substantial (240+) numbers. Naidu brought only 30+, and an outside support was okay in such a scenario. Whereas now, only 150 or so members will form the government, while another 160 will provide outside support. As you can see, this is certainl to cause instability.
Further, unlike Vajpayee, Sonia Gandhi doesn't have the nous to manage this kind of a difficult government. She is not thick skinned (she should be one) and was apparently very unhappy about BJP/RSS propaganda yesterday and almost tried to cop out. It took fair amount of persuation from the allies and her own party members to get her to accept the top job.
Let us hope that this government lasts its full term, for stability is very much necessary to sustain the 8+% economic growth in India.