Republican senators are putting Majority Leader John Thune on notice that finding 50 GOP votes for a $72 billion reconciliation package will be a heavy lift this week.

⚠️ Why it matters: Thune has two problems — substance and rushed timing.

• Retiring Sen. Thom Tillis (R-N.C.) started the week by emailing the entire GOP conference to say he will oppose the budget reconciliation bill in its current form, we scooped today.
• He's especially opposed to $1 billion for security related to President Trump's East Wing ballroom project and the Secret Service.

📣 Zoom in: Tillis is not alone.

• "I support his initiative," Sen. Lisa Murkowski (R-Alaska) said of Tillis. Murkowski doesn't like "these arbitrary deadlines that are set by the president just because he wants something."
• "I don't like things being shoved down my throat either," Sen. Ron Johnson (R-Wisc.) told us after saying he doesn't "necessarily disagree" with Tillis.
• "We literally have not had a discussion in terms of some of these added items, and that's something we should have," Johnson added.

🔥 State of play: Thune, who can lose up to three Republican votes, is plowing ahead anyway, saying he's planning a Thursday vote to "strike while the iron is hot."

• The Senate parliamentarian knocked out the first version of Secret Service funding, which includes $220 million for security upgrades to the East Wing.
• "We're trying to sort all that out and figure out how we can land the plane," Thune told reporters this afternoon.
• "Part of that involves the parliamentarian, and part of it involves the need to get 50 votes here in the Senate, and then 218 in the House."

Between the lines: Sen. Bill Cassidy (R-La.), who lost his primary election Saturday after being accused of disloyalty to Trump, indicated today that he would not thwart the GOP agenda simply because he lost.

• "I'm going to do what's good for my country and my state," he told reporters.

⏩ The bottom line: Some senators, including those who want to change the language around the Secret Service funding, think the Senate will act this week.

• "I think we'll move this week," said Sen. John Kennedy (R-La.).
• "I'm going to have an amendment to pay for the ballr — for the security funding. You guys call it ballroom funding, but only a small portion of it goes to the ballroom, and it's also security," he said.

— Hans Nichols

Republicans have fallen so badly in congressional polling that Senate seats in three Trump +10 states are in danger of flipping this year.

• 🌰 Ohio: Former Sen. Sherrod Brown (D) is running even with Sen. Jon Husted (R).
• 🐻 Alaska: Former Rep. Mary Peltola (D) is within the margin of error against Sen. Dan Sullivan (R).
• 🤠 Texas: State Rep. James Talarico (D) is polling competitively against Sen. John Cornyn (R) and Texas AG Ken Paxton (R).

🌊 Why it matters: This was supposed to be a friendly Senate cycle for Senate Majority Leader John Thune. But a D+11 environment could change the map.

• Republicans are down 50%–39% on the generic congressional ballot in the latest polling from N.Y. Times/Siena.
• Democrats are up 7.2% in the RealClearPolitics polling average of the generic ballot. The Siena poll is an outlier, but not wildly so.

‼️ The big picture: The GOP's Senate majority is in jeopardy unless the nationwide polling numbers bend back in their favor.

• Sen. Susan Collins (R) has a toss-up race in Maine against Graham Platner.
• North Carolina is slipping away with Republican Sen. Thom Tillis' retirement and former Gov. Roy Cooper in the race for Dems.
• This is important: Democrats are up 14 among those "almost certain" or "very likely" to vote, the N.Y. Times' Nate Cohn noted.

⏪ Flashback: The last time Republicans faced a potential wave was in 2018 — when they had the chance to challenge Democratic incumbents in Florida, Indiana, Missouri, Montana, North Dakota, Ohio and West Virginia.

• This time around they've got Georgia (Trump +2).

⛵️ The bottom line: The Democratic primary mess in Michigan is emerging as the GOP's lone bright spot.

• Republicans long ago united around former Rep. Mike Rogers, while Democrats are locked in a bruising three-way race among Rep. Haley Stevens, state Sen. Mallory McMorrow and former public health official Abdul El-Sayed.

— Justin Green