"The only presidential candidate to save President Park Geun-hye, who was martyred after being falsely accused, is candidate No. 2, Hong Joon-pyo," she said at the party's headquarters in Seoul.

The younger sibling urged supporters of her sister and their father, former President Park Chung-hee, to rally behind Hong to beat current front-runner Moon Jae-in of the liberal Democratic Party.

After struggling for weeks with a single-digit approval rating, Hong has emerged to challenge runner-up Ahn Cheol-soo of the center-left People's Party with nearly 20 percent.

Park called Hong a "descendant" of her "revolutionary" father and claimed the former prosecutor will achieve a revolution of the conservatives and average citizens.

"Please restore the honor of the lost Miracle of the Han River and the Park Chung-hee era, which wrote an epic for the nation," she said, referring to the country's rapid industrialization during her father's 18-year rule. "Please save President Park Geun-hye, who was incarcerated while trying to defend free democracy in solitude."

The former president faces the first preliminary hearing of her trial on charges of bribery and abuse of power on Tuesday. (Yonhap)