It has been a rather astonishing 24 hours in Congress. Last night, the Senate passed a bill which would force President Donald Trump to end American involvement in the war Saudi Arabia is fighting in Yemen, by a healthy margin of 54-46. Today, they followed this rebuke by passing the House bill to rescind Trump's "national emergency" declaration of a non-emergency on the southern border by an even-more-astonishing margin of 59-41. The House, not to be outdone, then unanimously passed (420-0) a resolution demanding that Special Counsel Robert Mueller's eventual report to the attorney general be made public. That's a whole lot of presidential rebuke for one single day, you've got to admit. And a whole lot of Republicans voting against a president of their own party.

The House vote is the least important, even though it garnered a unanimous majority. No Republican voted against it (there was one "present" vote, but no "nays"). But this is a non-binding resolution and Mitch McConnell is likely to just ignore it. Still, it shows the public's interest in finding out what Mueller knows is already a pretty potent political force in Washington.

Both of the Senate votes were much more momentous, especially when paired with the support in the House for both measures. The House originated the non-emergency declaration bill, and 13 House Republicans crossed the aisle to vote for it while no Democrats voted against it. The Yemen bill has already passed the House in a slightly-different form, and there will be a final House vote on the Senate's version within a week or so, but passage seems assured at this point.

Both of these votes are historic. Both are using provisions of laws passed in the 1970s to restrict executive power in ways that have never been done before. Congress has never voted to challenge a sitting president under the War Powers Resolution or the National Emergencies Act, even though the mechanisms for doing so have been there all along. And the Senate just voted to do so in both cases -- within a 24-hour period.

I went into greater depth about the historic nature of these votes a few weeks ago. Both measures are likely headed for the same ultimate fate -- Trump will veto them and Congress will not be able to overturn his veto, because the number of Republicans challenging the president has not risen to the point where either house has a two-thirds supermajority against him.

But that Senate vote today was certainly a lot closer to this goal than many had expected (including myself). Now, even with 12 Republicans crossing the aisle, 59 votes is still short of two-thirds by another eight votes. But it still means that almost one-fourth of all GOP senators voted to rebuke a president from their own party. And some of the ones that voted with Trump did so at their own peril. The most notable was Senator Thom Tillis, who had said he was voting against Trump right up until it became time to cast his vote. He even wrote an op-ed article exhorting his fellow Republicans to also vote for the measure. But when the chips were down, he chickened out and voted with Trump anyway. Tillis is up for re-election next year in North Carolina, so he may face some voter blowback for his vote today. As may other Republican senators in vulnerable seats who backed Trump.

Both bills may be vetoed, but the mere fact that Trump is even being forced to veto two important separation-of-powers bills is the real story here. Because he is essentially being forced to do so by his own party. After all, if Mitch McConnell had been able to keep his caucus together, neither bill would have arrived on Trump's desk in the first place.

To be blunt, Trump's grip on the Republican Party certainly seems to be slipping in a major way. This is a rather large split within party ranks, on two simultaneous fronts. Up until now, the Republicans have largely let Trump get away with just about anything he wanted to do, but that period may now be coming to a close. As the 2020 election gets closer, Republicans who are up for re-election have to weigh whether sticking with the president in an unpopular cause is going to hurt themselves politically or wind up helping them. Such schisms usually don't appear just before an election, it's worth noting.

The real question, of course, is whether the media is going to wake up and notice or not. They will write a "Democrats In Disarray" column at the drop of a hat, but they're often a lot slower to point out gaping chasms within the Republican Party. President Trump seems to be losing his grip on his own party, though, and that's going to be pretty hard to ignore. So far the defections are manageable for Trump (except that unanimous House vote, but Mitch McConnell will likely save him on that one when he refuses to bring it up for a vote in the Senate). Trump still holds enough of the party in his sway to avoid having a veto overturned. But the mere fact that he'll be issuing his first and second vetoes of his presidency is remarkable, because politically it shows his growing weakness within his own party's ranks. He just lost two votes in the Senate, one by a 54-46 margin and the other by a 59-41 margin -- even though the GOP holds a 53-47 majority in the chamber. That is downright astonishing, in the Trumpian era.

What it adds up to is a lot of Republicans willing to buck their own president and embarrass him politically. Whether this becomes an actual trend or not is still to be seen, especially considering that Mitch McConnell controls what the Senate votes on. Other measures where Trump could lose will probably not even ever get a vote, in other words.

Democrats should take the opportunity both to point out to the media this new revolt within the Republican Party against their own president and also to make the attempt to exploit this division further, on other unrelated matters. Because driving a wedge into the Republican ranks could pay off in all kinds of ways. And the deeper the division, the more pressure will mount on Trump to start signing some of these bills rather than vetoing them. It's certainly worth a try, after these historic votes. Because if Trump truly is losing his grip on the Republican Party, then Democrats should certainly do everything they can to help this process along.

-- Chris Weigant

Follow Chris on Twitter: @ChrisWeigant