The attack on voting rights in this country is partisan. The response must be partisan as well. But whether out of unspoken political concerns or genuine conviction, key Democrats in Washington do not have the stomach for the partisan combat it would take to stop that attack.

“The right to vote is fundamental to our American democracy and protecting that right should not be about party or politics,” Senator Joe Manchin of West Virginia wrote last month. “Least of all, protecting this right, which is a value I share, should never be done in a partisan manner.”

Senator Kyrsten Sinema of Arizona has taken a similar stance against partisan lawmaking on contentious issues. “The best way to achieve durable, lasting results?” she wrote in an op-ed for The Washington Post. “Bipartisan cooperation.” Ending the legislative filibuster to protect voting rights, she says, would be a mistake. “Would it be good for our country if we did, only to see that legislation rescinded a few years from now and replaced by a nationwide voter-ID law or restrictions on voting by mail in federal elections, over the objections of the minority?”

The problem with these arguments is that they can’t survive contact with a single, simple fact about American history: the fight to protect and advance the civil and voting rights of all Americans has always been more partisan than not.

Neither the 14th nor the 15th Amendments — which along with the 13th were the constitutional foundations for civil and voting rights in America — were passed on a bipartisan basis. The 14th Amendment passed on an almost total party-line vote in Congress, with Republicans standing against a Democratic Party that opposed federal intervention in the South. When legislatures in the states of the former Confederacy refused to ratify it, that same party-line majority passed the Reconstruction Acts in 1867 and 1868, which imposed military government on most of the South and made ratification of the amendment a precondition of readmission to the union.

The 15th Amendment was likewise partisan, passed on a party-line vote in both chambers of Congress. And while Republicans controlled most state legislatures at the time, the amendment still faced fierce opposition from Democrats wherever they could mount it. “In California, where the Chinese outnumbered blacks ten to one in 1870, linking the amendment to Chinese suffrage as a Democratic tactic to defeat the amendment was particularly successful,” the historian Wang Xi notes in “The Trial of Democracy: Black Suffrage and Northern Republicans, 1860-1910.”

“In Maryland,” he went on, “the all-Democratic legislature unanimously refused to ratify the Fifteenth Amendment in February 1870, and only when the ratification of the amendment by the requisite twenty-eight states appeared certain did the state pass a black registration bill.”

The Enforcement Acts of 1870 and 1871 — the first of which was an early voting rights bill (forbidding state officials from discriminating among voters on the basis of race) and the second of which gave the federal government the tools needed to prosecute the Ku Klux Klan — were also passed over unified Democratic opposition.