MILWAUKEE — On the ground at the RNC, Republicans say their mood is defiant after yesterday's assassination attempt.

Why it matters: Add the anticipation over Trump's first public speech since being shot —plus the unveiling of his VP pick — and you have a high-drama, high-unity convention.

• Trump's toughest primary opponent Nikki Haley pivoted overnight from not attending the RNC to being an invited speaker.
• Trump will be flying in today, he announced on Truth Social.
• The former president promised to be "defiant in the face of wickedness."

Zoom in: Trump co-campaign manager Susie Wiles and Trump campaign senior adviser Chris LaCivita told campaign staff to avoid their offices in D.C. and West Palm Beach, Fla., as they undergo security assessments, Axios' Sophia Cai, Stef Kight and Ivana Saric report.

• "The RNC convention will continue as planned in Milwaukee."

The bottom line: "The arena's set," RNC chair Michael Whatley said on "Fox News Sunday."

• "The security is here, and we feel very comfortable that we're working with the Secret Service, we're working with 40 different law enforcement agencies in terms of what that security is going to look like."

Tonight's Oval Office address, the third of his presidency, gives President Biden the opportunity to be the consoler-in-chief.

Why it matters: Biden is likely to use his address to call for unity and ask Americans to lower the partisan temperature in the country, as he did in earlier remarks today in the Roosevelt Room.

• Biden said he and Trump had a "short but good" conversation last night.
• "I am sincerely grateful he is doing well," Biden said.

Between the lines: The Oval Office address also allows Biden to focus the nation's attention on something other than his disastrous debate performance, which has led many of his fellow Democrats to call for him to step down.

• The president and his top advisers have been looking for moments to help Biden rehabilitate his image and demonstrate in words and deeds that he's up to running the country — and running for president.

Congressional Democrats' all-consuming angst over Biden's candidacy has taken an abrupt backseat in lawmakers' minds after the assassination attempt.

Why it matters: Democratic lawmakers say their immediate focus is on their personal security and that of their staffs, not on their party's political woes.

• A senior House Democrat told Axios that the Trump shooting has taken some of the heat off because it would "be bad form to make any statements against President Biden."
• Another Biden-skeptical Democrat, asked about lingering questions around the president's candidacy, told Axios: "I don't think that's the focus right now."

Go deeper.

Multiple Republican-led House committees are launching investigations into federal law enforcement's handling of yesterday's shooting, Axios' Juliegrace Brufke, Stef Kight and Andrew Solender report.

• FBI Director Christopher Wray said law enforcement "will leave no stone unturned" in its investigation, AP reports.

What we're hearing: Lawmakers are still scrambling for detailed information on precisely what happened during and around the shooting.

• House Speaker Mike Johnson (R-La.) was briefed yesterday, his office told Axios.
• A bipartisan pair of House members said today they plan to introduce a bill to enhance Secret Service protections for Biden, Trump and independent candidate Robert F. Kennedy Jr.

Between the lines: The Secret Service has already begun pushing back on some allegations that Trump was left inadequately protected.

• Agency spokesperson Anthony Guglielmi took to X to deny claims that "a member of the former President's team requested additional security resources and that those were rebuffed," which he called "absolutely false."
• "In fact, we added protective resources & technology & capabilities as part of the increased campaign travel tempo," he added.