The ongoing CBI investigation into the 2G spectrum scam appears to be the last straw which has led to the most serious crisis in the seven year-old strenuous relationship between the Congress and the Dravida Munnetra Kazhagam (DMK).
The DMK, which has been pushed to a backfoot in recent months with the arrest of former telecom minister A Raja which resulted in the party also losing the high profile ministry to the Congress, seems to have run out of patience with its senior ally.
The immediate provocation apparently is the strong indication from the investigating agency about the questioning of party MP, K Kanimozhi, the daughter of Tamil Nadu chief minister M Karunanidhi, in the near future.
Though the Congress has tried to explain to the DMK that there is nothing much it can do in the matter which is being monitored by the Supreme Court, the southern ally feels the noose being tightened around its leaders could have been prevented to an extent.
This is not for the first time that the two parties appear close to a breakpoint. Following the general election results in May 2009, the repeated deadlock on the induction of TR Baalu and A Raja in the union cabinet, had led to Karunanidhi announce a similar decision of extending outside support to the UPA government.
After much deliberations, the DMK agreed to keep Baalu out, but managed to retain the telecom portfolio for Raja. The five years of UPA-I between 2004 and 2009 had also seen moments of discomfiture between the two allies, but the issues were finally sorted out amicably.
The most glaring was the affidavit filed by the Shipping ministry on the controversial Sethusamudram project in Tamil Nadu in September 2007, which doubted the existence of lord Ram. The ministry was then headed by Baalu.
Following uproar by the opposition and even allies, the government withdrew the controversial affidavit.
Infact, the coming together of the Congress and the DMK in the run-up to the 2004 general elections was viewed as a major surprise development by political observers, given the allegation against the southern ally that it had a role in the assassination of former prime minister Rajiv Gandhi in 1991.
Between 1991 and 2004, the two parties remained sworn enemies of each other, till the ice was finally broken with a successful alliance, which now looks under a severe strain. The two parties first entered into an alliance in 1980, and it has been an on and off affair since then.