The Gujarat unit in-charge of the Congress party also praised ally Indian Union Muslim League (IUML) for retaining the Vengara assembly seat in Kerala in a byelection.
He termed the victory in Gurdaspur a mandate against the "anti-people" policies of the BJP government at the Centre, and a victory of Congress' policies under Rahul Gandhi's leadership.
Gehlot said the BJP should take lessons from its defeat.
"It is clear that people have understood that promises made by the government were all lies," he said in a statement, adding that the "countdown" for the BJP has begun.
Rajasthan Congress chief Sachin Pilot said support for the BJP was on a decline and people were now seeing "hope" in his party.
He said in a statement that the party would soon announce its candidates for by-polls on Ajmer and Alwar parliamentary constituencies in Rajasthan.