Valerie Jarrett is a lawyer and politician who was a senior adviser to President Barack Obama. The opinions expressed in this commentary are her own. View more opinion articles on CNN.

(CNN) With the midterm elections behind us, Democrats now have the majority in the House of Representatives. But one question remains: Who will lead the body?

A Democrat will once again raise the speaker's gavel, and he or she will face the monumental challenge of holding together a new, ideologically diverse majority while negotiating with Republicans.

Valerie Jarrett

The stakes couldn't be higher. And House Democrats cannot afford to put forward anyone less than their smartest, savviest, most tenacious and strategic member -- someone with a track record of successful leadership. That person is Nancy Pelosi.

As a senior adviser to President Barack Obama for eight years, I saw Pelosi lead in some of the most climactic negotiations and showdowns with the administration and Congress. During her time as speaker, Pelosi's ferocity -- in the face of all-but-impossible odds -- was essential to passing historic, progressive legislation into law, such as the Affordable Care Act that so many rely on for health insurance.

After the surprise election of Republican Scott Brown in 2010 to fill the seat vacated by the death of Sen. Ted Kennedy of Massachusetts, the Democrats were stripped of the 60th vote needed to avoid a possible GOP filibuster on the ACA. Some recommended Democrats retreat and settle for a children's health care bill.