(CNN) Nancy Pelosi, like most good politicians, usually avoids making predictions about what will happen in elections. Which is why what the House minority leader told late-night host Stephen Colbert on Tuesday night is worth paying attention to.

"Let me say this," Pelosi told Colbert . "Up until today, I would've said, 'If the election were held today, we would win.' ... What now I'm saying is, 'We will win.'"

She's almost certainly right. And the reason is, well, math.

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Let's go through the numbers starting with this one: 23. That's the number of seats Democrats need to net in order to retake the House majority in six days' time.

CNN currently rates 49 seats as either toss ups (30), leaning toward Democrats (14) or likely (5) to go for Democrats.

Of those 49, Republicans currently hold 42 -- including 29 toss-up seats, 10 lean Democratic districts and 3 likely Democratic ones. (One GOP seat -- New Jersey's 2nd -- is rated as solid Democratic.)

Give Democrats ONLY those Republican seats that are either solid, leaning or likely to go for them as of today and the minority party is more than halfway to winning back the House. Give Democrats the GOP seats that are leaning or likely to go for them and simply split the Republican toss-up races down the middle -- 14 for Democrats, 15 for Republicans -- and you have a 28-seat pickup for Democrats, more than they need to retake the House majority they lost in the 2010 election.

Assume that the toss-up races fall primarily for Democrats -- history tells us that one party tends to win the lion's share of the closest races -- and Democrats not only win the House but do so by a comfortable margin. If Democrats win 75% of all the races rated as toss-ups (and take all the GOP seats leaning or likely to go for the opposition party), you are talking about a gain of 40-plus seats.

A close look at the map suggests the potential for even larger Democratic gains is there. CNN currently rates 45 seats as either lean Republican (20) or likely Republican (25), and late-breaking data in other races , which isn't always reliable but could indicate last-minute surges, suggest real vulnerability for some other GOP incumbents.

The point here is that Democrats' upside -- like a young athletic swing man in the NBA draft -- is very high. And the party's own vulnerabilities are almost non-existent. Three Democratic-held seats are currently rated as toss-ups or worse: 1) Pennsylvania's open 14th District, where Rep. Conor Lamb (D) left to run (and likely win) in the 17th district; 2) Minnesota's 8th District, where Republican Pete Stauber is a slight favorite to win a Democratic seat; and 3) Minnesota's open 1st District. And, that's it. Three seats.

What that massive inequality in vulnerability means is this: Even in a national political environment that leans -- even slightly -- to Democrats, the party is extremely well-positioned to gain those 23 seats and perhaps many more.

That is, six days out from the election, a fact.