JP Nadda targeted Rahul Gandhi over the regime-change controversy.
Nadda accused the Congress of political opportunism and undermining democratic processes.
The ruling party asserted that democratic mandates are determined solely by elections.
The JD(U) on Thursday accused Congress leader Rahul Gandhi of "opportunistic politics" by associating with people who talk about regime change instead of seeking to oust the government through elections.
Speaking to PTI, JD(U) national spokesperson Rajeev Ranjan Prasad said Gandhi should seek a public mandate, build trust among people and win elections democratically instead of associating with those talking about regime change.
"Rather than talking about regime change or being seen alongside people who talk about regime change, you (Rahul Gandhi) should go among the people, seek their mandate, build public trust and win elections," he said.
"The elected government has received a significant mandate from people of the country. If you are seen alongside people who talk about overthrowing such a government, it reflects opportunistic politics," Prasad said.
He said people do not expect such conduct from Gandhi, adding that the opposition, too, shares the responsibility of upholding democratic values.
"In a democracy, there are high expectations from the opposition. And you are leader of opposition, not merely a Congress leader," he said.
Prasad described Gandhi's conduct as irresponsible and said it affects the Congress, as well as the credibility of the wider opposition.
"This is irresponsible conduct. You will have to bear the consequences, and you are also bringing the credibility of the entire opposition under scrutiny," he said.
The remarks come amid a political debate over regime change following advocate Prashant Bhushan's remarks linking the opposition's agitation over alleged irregularities in electoral rolls and its demand for Chief Election Commissioner Gyanesh Kumar's removal to a broader political objective.
