KIEV, Ukraine — WHEN she moved into her office as deputy speaker of Parliament a little over a year ago, Oksana I. Syroyid hung a large oil painting called “The Edge of the Sky Is Glowing.” It shows a man turning his back on the viewer while flames burn on the horizon.

“This,” she said, “is every oligarch and every Russian agent who is still in Ukraine.”

With her own fast burn of ambition, ferocity and style, Ms. Syroyid of the center-right Self-Reliance party, a former law professor, has shot to the top of Ukrainian politics. A political insurgent, she has made a signature issue of derailing a peace agreement with Russia and, in the process, may have eclipsed the former prime minister, Yulia V. Tymoshenko, as the most powerful female politician in Ukraine.

A 39-year-old native of the Lviv region in the country’s nationalist west, Ms. Syroyid talks boldly about Ukraine acting in its own interests, not those of outside powers. “We need to stop thinking of how to counter Putin, or how to please all our partners,” she said in a recent interview.

The question many here ask is whether Ms. Syroyid, a relative newcomer, can somehow master the byzantine structure of Ukrainian politics and emerge as the one to lead the country out of the morass of corruption and government dysfunction that threatens its future. Or, is she just another in a line of ambitious upstarts causing Western governments their latest headache in Ukraine and, possibly, taking the country down with her?