The changes mean that Republicans now have 78 seats in some form of political peril as compared to just 40 for Democrats. If Republicans lost only the seats they hold that CNN currently rates as toss-ups or leaning toward Democrats, they would lose 28 seats -- five more than Democrats need to retake the majority.
Yes, the election isn't tomorrow. In fact, November 6, 2018 is still 190 days away.
But the trend line has to concern Republican strategists charged with holding onto the House majority. With each passing week, more GOP-held seats come online as competitive -- widening Democrats' margin for error and stretching the Republican cash devoted to keeping the majority that much thinner.
Of the 12 seats CNN moved on Monday, Trump won all of the districts; he carried three by single digits and nine by double digits -- including two that he won by more than 20.
Everyone knew that 2018 would be a tough year for Republicans, given historic trends against the party who holds the White House. Trump's inability to move his job approval numbers much above 40% compounds those problems as does the fact that he has been, to date, the best turnout driver Democrats could possibly hope for.
The Point: If districts that Trump won in 2016 by 10 to 15 points are competitive this fall, the GOP House majority is as good as gone. The only important question will be how many seats Democrats can pick up.