A CNN report explains why it would be hard for U.S. House Democrats to boot San Francisco liberal Nancy Pelosi as their leader.

Nancy Pelosi is sending a defiant message to House Democrats who are grumbling about her leadership: Come at me.

But while Pelosi’s critics are increasingly vocal, they have not yet answered critical questions about who would fill her leadership and fundraising roles if they were to mount a serious challenge for the perch atop the party Pelosi has held since 2002. Nor have they identified a challenger.

At least, not yet. …

… Still, Democrats would have massive gaps to fill if they were to oust Pelosi.

Chief among those is fundraising. Since 2002, Pelosi has hauled in $568 million for House Democratic campaigns — including $141 million during the 2016 campaign cycle.

Pelosi also has a long history of holding her party together through difficult votes — enabling former President Barack Obama to shepherd into law a series of Democratic-backed measures in 2009 and 2010 and later forcing Republicans to grapple with the politically damaging divisions within their own ranks.

No other Democrat possesses the stature to match those accomplishments.

That reality was the subtext for Pelosi’s taunting remarks Thursday in which she cast her Democratic critics as hungry for attention rather than serious about ousting her.