House and Senate Republican leaders are heading to Dallas to embrace the president who has done the most to shape — and complicate — their political fortunes.Why it matters: Majority Leader John Thune and Speaker Mike Johnson don't have much of a choice about attending September's midterm convention. President Trump doesn't tolerate high-profile dissent, and both leaders know their best chance of staying in power is by staying united.But for Republicans in tight races, the two-day political extravaganza presents a difficult choice.They can stand shoulder-to-shoulder with Trump, raise money from big-dollar donors and bask in the MAGA media glow.Or they can stay home and create some separation from a president whose approval ratings are sinking.Zoom in: Sen. Dan Sullivan (R-Alaska) and former GOP Rep. Mike Rogers, who is running for U.S. Senate in Michigan, are both planning to attend, according to people familiar with the matter. So is Texas Attorney General Ken Paxton, another GOP Senate candidate.However, Sen. Susan Collins (R-Maine), the only Republican who represents a state that President Trump lost, is unlikely to make it and will be campaigning in her home state, according to a person familiar with the matter.Spokespeople for Sen. Jon Husted (R-Ohio), Rep. Ashley Hinson (R-Iowa), Rep. Mike Collins (R-Ga.) and Michael Whatley, the GOP Senate nominee in North Carolina, declined to comment or didn't preview their boss' plans. Hinson and Collins are also seeking Senate seats. In addition to Johnson, Majority Leader Scalise (R-La.) and Majority Whip Tom Emmer (R-Minn.) plan to attend. National Republican Senatorial Committee Chair Tim Scott (R-S.C.) and National Republican Congressional Committee Chair Richard Hudson (R-N.C.) are both scheduled to be in Dallas.Zoom out: The Sept. 9-10 convention is still six weeks out, and senators and representatives have never been confronted with a mid-September, mid-cycle political convention.Party committees are starting to ask donors about attendance, but details — and programming — are sparse."The upcoming Midterm Convention is an opportunity for Republicans across the country to rally behind President Trump's America First agenda that's brought lower drug prices, lower taxes, and a secure border," RNC national press secretary Natalie Baldassarre said.What they're saying: "I'm proud that Dallas will host the RNC Midterm Convention this September," said Sen. Ted Cruz (R-Texas)."Texas is leading the nation in defending freedom and advancing conservative principles, and I look forward to welcoming Republicans from across America as we celebrate the landmark victories achieved this Congress and work together to elect Republicans up and down the ballot in November." The intrigue: For all the sniping between Trump and Thune this week, the majority leader recognizes that he and Senate Republicans stand a better chance of victory by presenting a united front.But he'll be in Dallas during a Senate recess that the president wants canceled until the SAVE Act is passed.The bottom line: The convention is expected to be part pep rally, part "Friday Night Lights": Clear eyes, full hearts — and Republicans hope the last line writes itself.