"If there is one regret that I have in politics, it is that I was made to fight Rajesh Khanna from Delhi in 1991," Sinha revealed in his biography "Anything But Khamosh" slated to be released on Wednesday.
Sinha revealed that losing the electoral battle was one of his rare moments of dejection and he had apologised to Khanna.
"For this, in his lifetime, I had apologised to Rajesh Khanna both directly and indirectly. Under no circumstances should I have started my active political career with a bye-election. But I couldn't say no to (L.K.) Advani ji, who was my guide, guru and ultimate leader," Sinha said in the book.
Advani, who had contested and won the 1991 elections from Gandhinagar and New Delhi, had opted for his seat in Gujarat.
In the bye-election that followed for the Delhi seat, then political novice Sinha was brought in by the BJP to counter the Congress candidate Rajesh Khanna.
Sinha insisted that he joined the party and fought the bye-election "Only because of the persuasion of Kalyan Singh, Shanta Kumar, Madan Lal Khurana and other party leaders.
"I had initially resisted all their overtures but I was finally taken before Advani ji, and he had said, 'It's a question of our prestige and I don't want to hear a 'No' from you this time."
"When I lost that election, it was one of my rare moments of dejection," he said.
"It was the one time I really cried. I also felt very let down because Advani ji had not come even for one day to campaign for me."
Terming his debut electoral loss a "misstep", Sinha revealed that it was a terrible time for him.
"Politics showed its ugly profile in many ways. After I lost that election, I was so sharply sidelined that I would be made to feel distinctly unwelcome at our party office on Ashoka Road. People would stop talking when I entered, or change the topic and make me uncomfortable.
"One day, a party official who is still with the BJP, came up and told me, 'Shatruji, please sit outside. We'll call you when we're ready to talk to you'," he remembered.
"That went straight to my heart and hurt me so badly, that for years, I never visited the office," he added.