"Jagan benefited from the sympathy. But that will only be a temporary gain and the real test will be the 2014 elections," Chandrababu told reporters, in reaction to the by-poll results in which his party was routed in all the 18 Assembly constituencies.
He blamed the ruling Congress for failing to take "timely action" against Jagan over corruption.
"The way in which he was arrested...His mother's and sister's campaign all generated some sympathy for Jagan and that helped the YSRC," he said.
The TDP had fought relentlessly on various issues like corruption, agrarian crisis and other problems of the people, he said. "Our target is 2014 and we shall continue to fight on all issues concerning people."
The party would deliberate on the by-election results and take necessary corrective steps, the former Chief Minister said.
Replying to a question on the Presidential election, Chandrababu said the decision on who to support would be taken after a discussion in the politburo tomorrow.
He refused to comment on UPA's choice of Pranab Mukherjee for the President's post.