House Speaker Paul Ryan said yesterday that he was “not ready” to endorse Donald Trump for president. This is a serious moment for the Republican Party; the presumed presidential nominee does not have the support of the highest ranking member of the party or the full support of staunch Republican donors like Charles Koch, who recently stated that it was “possible” he could support Hillary Clinton.

Unfortunately for Paul Ryan and Charles Koch, they seem to be out of options for an alternative Republican candidate – the Indiana primaries this week saw both Ted Cruz and John Kasich dropping out of the race leaving Donald Trump a clear path for his party’s nomination. Trump used the national spotlight to spell out what his first 100 days in office might look like were he to be the nation’s 45th leader: the wall with Mexico would be designed with the help of Homeland Security to bar migrants from coming into the U.S.; an immigration ban on all Muslims would be implemented; the Federal Reserve would be audited; serious efforts would be underway to repeal the Affordable Care Act; and American companies outsourcing jobs abroad would face stiff tariffs.

Trump’s policy plans have very troubling implications for the future of the United States. With little public service experience, he is yet to demonstrate an understanding that being president will require him to carry out tasks – from the mundane to the strategic – like building a cabinet, winning the confirmation of a new Supreme Court justice, surrounding himself with policy experts, seeking nuanced advice from seasoned diplomats on America’s leadership role in the world’s hotspots, allaying the alarm with which many European leaders and other close allies view him, addressing ever-deepening  inequality in the country while building confidence that American businesses can succeed, and mending the racial rifts in our society. These are only a handful of challenges that a hypothetical President Trump will have to face.

The Republican Party is at a crossroads. Trump may be a successful businessman, a real estate developer and a reality television star. But being the President of the United States requires other skills and values – including a strong belief that diplomacy works and a deep and unwavering commitment to the public good. If Trump decides to move beyond inflammatory campaign rhetoric and begin to present real policy solutions that could actually be implemented in our current political system, he may be able to bring in the much-needed support from his own party. Until that happens, however, he will continue to threaten the credibility of the Republican Party, which could have implications long after the 2016 election.

Shyama Venkateswar is Director of the Public Policy Program at Roosevelt House and Distinguished Lecturer at Hunter College. In this capacity, she leads the Public Policy Program’s undergraduate curriculum, teaches the senior Capstone Seminar, co-manages faculty initiatives, works closely with city & state agencies for student internships, manages adjuncts, and directs a scholars program funded by the Jewish Foundation for Education of Women. She is a regular columnist for Roosevelt House’s website on a variety of national and global policy issues on conflict resolution, food security, women’s leadership, criminal justice reform, among others. She has almost twenty years of experience in research, policy and advocacy focusing on social justice issues, both in the U.S. and globally. Before coming to Hunter College, she worked at the National Council for Research on Women (NCRW), where she served as Director of Research & Programs, and helped provide the vision and strategic direction for the Council’s policy agenda on economic security for low-income women, diversity in higher education and the corporate arena, women’s leadership, and ending global violence against women. She is co-author of two NCRW reports, Caring for Our Nation’s Future; and The Challenge and the Charge: Strategies for Retaining and Advancing Women of Color in addition to numerous commentary and opinion pieces on poverty, job creation, peace-building, and immigrant rights published in The Miami Herald, The San Francisco Chronicle, The Philadelphia Inquirer, Asia Times, The Indian Express, and the Chicago Sun-Times. She has given Congressional briefings, and presented her research findings to academic, policy, advocacy and corporate audiences. She received her Ph.D. in Political Science from Columbia University and is a graduate of Smith College.