Saldanha was pitted against two contestants D'Sa (Congress) and Ramakant Borkar (Independent).
On the last day of withdrawal of nominations, both the candidates withdrew, setting the stage for Alina Saldanha getting elected unopposed from the constituency.
"I am withdrawing because I am not getting necessary support from Congress," D'Sa said minutes after applying for withdrawal from the fray.
The by-poll in Cortalim was necessitated after the death of BJP legislator Matanhy Saldanha. The election was slated on June 4.
D'Sa's withdrawal from the fray was unexpected for Congress which was hoping to salvage its pride by winning the bypoll.
The party was reduced to single digit number in the state legislative assembly after March 3 Goa assembly election which saw BJP coming back to power.
Another legislator, Ramakant Borkar, who initially wanted to contest on United Goans Democratic Party (UGDP) ticket, had expressed his wish to be independent candidate. He too applied for the withdrawal.
Chief Minister Manohar Parrikar told reporters that Alina would be inducted in the state cabinet within a fortnight.