Modi, who was in the national capital to attend a chief ministers' conference, told reporters, "Today the people of Gujarat have given a massive win to BJP.
Congress has been badly defeated. Loss of Congress in Lok Sabha seats is message of people's anger. This is an ultimatum to the government in Delhi."
He thanked the voters of Gujarat for BJP's victory in by-polls to two Lok Sabha and four Assembly seats. All the six seats were held by Congress.
Later Modi met Rajnath Singh at the latter's residence to celebrate the impressive victory. Emerging from his meeting with Singh, Modi said, "The people of Gujarat have given the message to the UPA government that it is time for it to go."
Singh congratulated Modi and the Gujarat BJP unit chief as well as party workers for the good performance in the by-polls.
"There is anger among the people against the UPA government for its failures. This victory shows that BJP will get a thumping win in the Lok Sabha polls," Singh said.