Congress president Mallikarjun Kharge felt dizzy while addressing a public rally on Sunday in the Jasrota belt of Jammu and Kashmir's Kathua district.
He is now stable and doctors are attending to him, party leaders said.
Kharge was paying tribute to a head constable who was killed in an ongoing operation with terrorists in Kathua.
Two other police personnel have been injured in the incident and one terrorist has been killed.
"He was addressing a public rally in Jasrota when he felt uneasy and dizzy. His colleagues helped him into a chair," Congress general secretary Gulam Ahmed Mir said.
He added that the Congress president is stable.
Kharge had flown to Jasrota to address a rally to garner support for his party candidates in the assembly polls. -- PTI