The BJP is likely to announce its pre-poll alliance with AIADMK and a few other regional outfits in Tamil Nadu next week after union minister Piyush Goyal held midnight parleys with chief minister EK Palaniswami and his deputy O Panneerselvam.

People aware of the talks between the parties said the announcement will be made in Chennai in the presence of BJP top brass and the AIADMK leadership.

One of the people involved in the alliance discussions said: "There were some challenges in making this happen. At least five rounds of talks were held. The deal was sealed after Piyush Goyal came down to Chennai."

While deal is finalised, seat sharing negotiations are still underway as sources say the BJP wants to contest at least 8 seats this time around.

The source said both parties are "confident" that the PMK will also board the alliance train.

The DMDK, led by Vijayakanth, Tamil Maanila Congress led by GK Vasan, and two other regional parties are also likely to be part of the alliance.

While the announcement is due for Tuesday, it is expected that alliance partners might share the stage during Prime Minister Narendra Modi's rally in Kanyakumari on March 1.

The BJP had planned a series of visits by top leaders such as Nitin Gadkari and others to meet with the party cadre, industry groups and social groups but they are likely to be rescheduled after the terrorist attack in Pulwama on Thursday.

In Tamil Nadu, the AIADMK-BJP alliance moved to seal the deal with a formal announcement much after the DMK revealed its intentions to side with the Congress.

Stalin has made a head start in reaching out to the people through his 'gram sabha' programm wherein he conducts small public meetings with people in the hinterland. The programme has been going on for more than a month now.

However, the DMK has not formally announced that it will go to polls with the Congress, so far.

Politically, the BJP-AIADMK alliance means that the larger parties in Tamil Nadu have aligned themselves with the national parties for the parliamentary polls, leaving the others such as TTV Dhinakaran's AMMK and the new outfit by actor Kamal Haasan to chart out their own paths.

Haasan had recently indicated that he will not align with either of the two large Dravidian parties to "avoid the stain of corruption."