President Joe Biden used the 100th anniversary of Tulsa’s race massacre to make a plea for sweeping legislation in Congress to protect the right to vote as Republican-led governments in Texas and other states pass new restrictions making it tougher to cast ballots.

Biden, marking the centennial in Oklahoma on Tuesday, called out lawmakers in Congress — including two senators in his own party — for holding up action on voting bills. Invoking the words of the late Rep. John Lewis, Biden said the right to vote is “precious” and must be protected. He pledged that June will be a “month of action” on Capitol Hill as Congress considers the legislation, which is among the top priorities of his administration.

“We’re not giving up,” Biden said. “I’m going to fight like heck with every tool at my disposal for its passage.”

Republican state legislators are pushing what experts say is an unprecedented number of bills aimed at restricting access to the ballot box. While Republicans say the goal is to prevent voter fraud, Democrats contend that the measures are aimed at undermining minority voting rights.

Most recently, the Texas Legislature moved closer to passing a bill that would reduce early voting hours, tighten voter identification requirements for absentee ballots and eliminate ballot drop boxes and drive-thru voting centers. The bill was blocked only when Texas Democrats walked off the House floor on Sunday night; Republican Gov. Greg Abbott has said he will order a special session to ultimately ensure its passage.

Senate Republican leader Mitch McConnell played down the ability of the new state laws to quash voter turnout.

“I don’t think any of these efforts at the state level are designed to suppress the vote based upon race,” McConnell said at a news conference Wednesday in Kentucky.

McConnell promised to block the federal voting rights bill, characterizing it as undue government overreach into state election systems. He said no GOP senators support it.

Biden addressed the federal voting rights legislation during an event marking the 100th anniversary of the Tulsa race massacre, in which a white mob looted and burned Tulsa’s Greenwood district, which was known as Black Wall Street.

Despite Biden’s pledge to keep fighting to pass legislation protecting voting rights, he acknowledged that his biggest obstacle may be within his own party.

Biden called out two fellow Democrats in explaining why he hasn’t enacted some of the most ambitious elements of his agenda, noting that slim majorities in the House and evenly divided Senate have hamstrung legislative negotiations around key issues like voting rights.

Responding to critics who question why he hasn’t been able to get a wide-reaching voting rights bill passed, Biden lamented, “Well, because Biden only has a majority of effectively four votes in the House, and a tie in the Senate — with two members of the Senate who voted more with my Republican friends.”

It appeared to be a reference to Democratic Sens. Joe Manchin of West Virginia and Kyrsten Sinema of Arizona, both of whom have frustrated Democrats with their defense of the filibuster. The rule requires most legislation to win 60 votes to pass, making many of Democrats’ biggest priorities like voting rights and gun control dead on arrival in the 50-50 Senate. While Sinema is a sponsor of the voting rights bill that passed the House, Manchin has refused to sign on, calling the measure “too broad.”

White House press secretary Jen Psaki on Wednesday denied that Biden was blaming Manchin and Sinema for holding up the legislation. She said Biden does not see “eye to eye on every single detail of every issue” with every lawmaker, but that he simply was referencing the commentary he often hears on cable TV about the slow progress on legislation he wants to sign into law.

“I don’t think he was intending to convey anything other than a little bit of commentary on TV punditry,” Psaki told reporters after being pressed to explain what Biden meant.

But it’s not just Manchin and Sinema who oppose doing away with the filibuster, As many as 10 Democratic senators are reluctant to change the rules even for must-pass legislation such as the voting rights bill. Biden has not said he wants to end the filibuster.

It’s unclear whether Biden’s comments will change the views of any senators, who are facing tough choices ahead as pressure mounts on them.

Senate Majority Leader Chuck Schumer, D-N.Y., told colleagues that he would be bringing the voting rights bill to a vote the week of June 21, in effect testing where senators stand. Schumer warned in a letter to colleagues last week to brace for the month ahead.

Biden has tasked Vice President Kamala Harris with leading the administration’s efforts to defend voting rights. It adds another high-profile fight to Harris’ fast-expanding portfolio, which includes addressing the root causes of migration from Central America, leading the National Space Council and working on expanding access to broadband internet.