You could say Sens. Joe Manchin and Joe Donnelly faced a tough choice on Thursday’s vote about taxpayer funding of Planned Parenthood, America's largest abortion provider. But for Democrats, there is no choice on abortion anymore. You simply do what the abortion lobby tells you to do.

Every Democrat voted against Sen. Rand Paul’s amendment to end federal funding of Planned Parenthood, which as Paul explains, “ends the lives of 320,000 babies every year. That’s about 900 babies every day.”

That's also one out of every three abortions performed in the United States each year.

The abortion giant, funded by liberal elites who share its dedication to thinning the population of “unwanted” babies, rakes in more than $400 million of your money every year. The official line is that none of that $400 million pays for any of those 320,000 abortions. But the fungibility of money makes this one of the most obvious and odious pieces of political casuistry. Federal dollars force all taxpayers to keep afloat a business, the core purposes of which are to abort unborn people and lobby Washington to pay the people who do it.

If principle held sway, one could not explain why Donnelly and Manchin, who claim to be moderate centrists, would take such an extreme position. It is extreme to argue that everyone who pays taxes should be forced to subsidize the biggest practitioner in this most controversial of industries. About 60 percent of the public opposes taxpayer funding of abortion. A clear majority of voters in Indiana and West Virginia, the states that Donnelly and Manchin represent, believe abortion should be illegal in most cases. You’d think centrist senators could meet their voters in the middle and be pro-choice on both abortion and on funding the abortion industry.

Donnelly used to vote that way. Before 2016, he repeatedly voted against federal funding for Planned Parenthood. So, what happened?

Only Donnelly can see into his own conscience, but it’s pretty obvious, if you’ve watched the Democratic Party change in recent decades. Abortion has become the beating heart of the party. This practice, which our civilization proscribed from at least the drafting of the Hippocratic Oath until the passage of the Geneva Conventions, is the adamantine center of the Democrats' fundraising apparatus. It is the party's only non-negotiable tenet.

When President Barack Obama entered into budget fights with Congress, for instance, he was willing to budge on tax cuts for the rich, military spending, domestic spending — anything except funding for Planned Parenthood. Federal abortion funding was his only sacred precept.

The group that has spent the most for Democrats this election so far is “Women Vote!” the super PAC of EMILY’s List, the raison d'etre of which is to keep abortion legal and subsidized. The Democrats’ second-biggest individual financial donor this year is Donald Sussman, who is also the lead funder of Planned Parenthood of Northern New England. The top donor, Tom Steyer, as an explicit rule, only funds abortion-friendly candidates.

Unless you'll defend and subsidize abortion, there's no Democratic money out there for you. Party leaders are surrogates for the business, carrying out the orders of these extremists. The party refused officially to back Rep. Dan Lipinski, D-Ill., in his recent primary challenge because he is moderately pro-life.

The phrase "litmus test" doesn't capture the centrality of abortion in today's Democratic Party. It is the sine qua non of being a Democrat. It is the threshold issue for the party. No one comes to the party except through Planned Parenthood.

To today's Democrats, abortion is like slavery was to Democrats in 1860: Mere tolerance of the institution is not enough. Saying it should be allowed is inadequate. One must endorse the legitimacy of the institution by making every taxpayer tithe to its chief practitioner.

So, why did Manchin and Donnelly vote to force their constituents to subsidize the abortion industry? Because they didn't have a choice.