House Minority Leader Kevin McCarthy (R-Calif.) on Friday joined 125 House Republicans in backing the Texas lawsuit that seeks to invalidate the millions of votes in four battleground states that President-elect Joe Biden won.

Why it matters: McCarthy was left off of the original filing on Thursday and would not answer questions about whether he supported the long-shot lawsuit, which has been dismissed by legal experts as doomed to fail. He is now the highest-ranking Republican in Congress to back the suit, which President Trump has called "the big one."

• By signing the amicus brief, the GOP members are encouraging the Supreme Court to hear arguments in the case, even though all 50 states have certified their election results and no evidence of widespread fraud has been uncovered.
• The lawsuit alleges that Georgia, Michigan, Pennsylvania and Wisconsin skewed the presidential election results and electors selected by voters in those states should not be permitted to cast votes for Biden.

What they're saying: “This brief presents [our] concern as Members of Congress, shared by untold millions of their constituents, that the unconstitutional irregularities involved in the 2020 presidential election cast doubt upon its outcome and the integrity of the American system of elections,” the brief signed by GOP lawmakers states.

Details: Signatories include House Minority Whip Steve Scalise (La.) and National Republican Congressional Committee chair Tom Emmer (Minn.) Rep. Mike Johnson (R-La.), head of the conservative Republican Study Committee, led the effort to solicit signatures.

• The total amounts to 64% of the House GOP caucus, after 20 members — including McCarthy — joined on Friday.

The other side: GOP Conference chair Liz Cheney (Wyo.) is among the high-profile Republicans who did not back the suit.

• Rep. Chip Roy (R-Tex.) wrote on Twitter that the case “represents a dangerous violation of federalism” and “sets a precedent to have one state asking federal courts to police the voting procedures of other states.”

The big picture: 17 states filed a brief in the Supreme Court this week in support of Texas, including Alabama, Arkansas, Florida, Indiana, Kansas, Louisiana, Mississippi, Montana, Nebraska, North Dakota, Oklahoma, South Carolina, South Dakota, Tennessee, Utah and West Virginia.

• Trump filed a motion to intervene in the case on Wednesday.