India's government faces a confidence vote on Tuesday to prove its parliamentary majority after its communist allies withdrew support earlier this month over a controversial nuclear deal with the United States.
If every lawmaker votes, the government needs to reach the 272-member mark in the 543-member lower house of parliament.
Newspaper and television tallies give Singh's government an edge of between two and four votes over the Opposition in parliament, but said several MPs remained undecided.
Here is a look at political parties and their numbers, according to the latest figures available at the Indian parliament's website (http://parliamentofindia.nic.in/) and to party officials.
These numbers could possibly change as negotiations between parties continue.
PRO-GOVERNMENT - Around 266 seats
* United Progressive Alliance - 226 members. The UPA is made up of Congress party with 153 members, the northern Indian regional party Rashtriya Janata Dal with 24 members, and the southern Indian party Dravida Munnetra Kazhagam with 16 members. The alliance also includes another eight smaller parties and a rival lawmaker from the opposition Hindu-nationalist Bharatiya Janata Party.
* Samajwadi Party - 39 members. This regional party from northern India holds the balance of power. They will replace the Communists, supporting the government. But there are signs of a split within the party over supporting the nuclear deal and at least four to five lawmakers could switch sides.
SMALL AND INDEPENDENT PARTIES - Around 28 seats.
* There are 28 independents and smaller parties, including the southern Kerala Congress with two, the Mizo National Front with one and others whose stand and votes could prove crucial. Some have stated their position while others have stayed silent.
THE OPPOSITION - Around 249 seats
* Communist parties - 59 members. The four parties are expected to stand against the government in parliament during a vote of no-confidence.
* The National Democratic Alliance - 170 members - This opposition alliance is led by India's main opposition group, the Hindu nationalist Bharatiya Janata Party (BJP), which has 129 lawmakers after one of them joined the government alliance.
* The regional caste-based Bahujan Samaj Party (BSP) has 17 members and recently withdrew support to the ruling government.
* The northern Indian party Rashtriya Lok Dal has joined the opposition bench with three members.