"Only then it will be clear who stands with whom and only then will we come to know about the secular credentials of different parties," he said, replying to a question about post-poll alliance the Congress was looking at.
The elections for the 15th Lok Sabha are widely expected to throw up a fractured verdict with no single party or present political alliance getting the required majority to form the government.
The Congress is believed to be wooing Bihar's ruling Janata Dal-United (JD-U) for a possible post-poll tie up. Congress' Rahul Gandhi had lavished praise on Bihar Chief Minister Nitish Kumar earlier this week.
However, the JD-U has denied it was leaving the Bharatiya Janata Party (BJP)-led National Democratic Alliance (NDA).
Dwivedi said: "Till any party is with the BJP, we will not consider it secular. Those who want to come with us will have to leave the BJP."
He said the Samajwadi Party (SP), the Rashtriya Janata Dal (RJD) and the Lok Janshakti Party (LJP) were still with the Congress-led United Progressive Alliance (UPA).
"Have they said that they are not with the UPA?" he asked, when queried whether the RJD-LJP combine in Bihar and the SP in Uttar Pradesh were fighting the elections against the Congress.