MANILA - (UPDATED) Taguig Rep. Pia Cayetano filed her certificate of candidacy for senator on Tuesday, setting the stage for her comeback on the national political stage.

A known fitness buff, Cayetano rode a bicycle from the Rizal Monument to the Commission on Elections main office in Intramuros, Manila to file her COC.

This, she told radio DZMM, symbolizes her advocacy, which includes sustainable transportation.

Pia Cayetano, who will be filing her COC today, biked from the Rizal Monument to the Comelec office. | via @PatrickRQuintos #Halalan2019 pic.twitter.com/jAUQNodzvY

— ABS-CBN News (@ABSCBNNews) October 16, 2018

Asked if she will also champion the shift to federalism pushed by her ally President Rodrigo Duterte, the lawmaker said this system of government is "good in theory" but lawmakers still need to scrutinize several versions of its proposed constitution.

Cayetano served the maximum 2 consecutive terms in the Senate from 2004 to 2016. Her brother is Foreign Affairs Secretary Alan Peter Cayetano.

She is placed third in Pulse Asia's Sept. 1 to 7 poll on senatorial preferences, behind incumbents Grace Poe and Cynthia Villar.

Cayetano enjoys the backing of the president's daughter, Davao City Mayor Sara Duterte-Carpio, who chairs the regional party Hugpong ng Pagbabago.

• Sara Duterte nixes congressional bid, endorses Pia Cayetano, Mocha Uson

Despite her ties to the first family, Cayetano, a women's advocate, has spoken out in several instances against the President's actions that drew the ire of some groups, including his joke about the rape of an Australian missionary and his wolf-whistling at a reporter.

• Pia Cayetano: Joking about rape not funny

She sponsored the Reproductive Health Law, which promotes information on and access to family planning methods; the Sin Tax Reform Act that raised duties on cigarettes and liquor; and the Graphic Health Warning Act that required cigarette packages to bear photos of the hazardous effects of smoking.

As a congresswoman, she recently pushed for a measure seeking up to 105 days of paid maternity leave.

POLITICAL DYNASTY?

Her brother Alan Peter Cayetano will run as congressman of Taguig, while her other sibling Lino Cayetano is seeking the city's mayoral post, she said.

• Cayetano eyes Speaker post in House comeback bid

She said her values may be the same as that of her siblings, but their advocacy are different.

"Ibang-iba ang laban namin. Iyung kakayahan ng tumatakbo, iyun ang tingnan ninyo, huwag iyung apelyido," she told voters.

(Our fights are different. Look at the capabilities of a candidate, not his or her family name.)