Trump's third presidential nomination has the potential to be the most lasting and difficult challenge Pierre Poilievre's team will face.This past Tuesday, former President Donald Trump announced that he will seek the 2024 Republican presidential nomination. Donald Trump is a polarizing figure in the United States, but in Canada, he is downright detestable to the vast majority of voters. Trump unites Canada's left and divides the right. Some polls suggested that Trump had as little as 16 per cent support among Canadians when he was defeated by Joe Biden. Given the events of January 6, Trump presumably has only become more detestable among Canadians, so how will his candidacy impact federal Conservatives?First, Trump will be a challenge for caucus discipline because many current Conservative Members of Parliament (MPs) support Donald Trump. While most of these MPs know that it's not politically advantageous to show outward support for the former President (remember what happened to Candice Bergan when she wore the MAGA hat), a small number will inevitably give their unfiltered opinion when they think it's safe to do so. The result will be a slow trickle of pro-Trump content that the Liberals will use to showcase support and sympathy for Donald Trump by Team Poilievre.This situation will result in the Opposition Leader's Office (OLO) constantly trying to dissuade Conservative MPs from speaking publicly about Trump, but in such a way that those same MPs don't complain anonymously to the media that Poilievre's office has become the gatekeeper. This is a tough set of circumstances that rarely end well. I don't envy the OLO communications team for having to navigate this situation.Second, Trump will challenge Poilievre's ability to maintain message discipline. Donald Trump's Canadian support is entirely comprised of traditional conservatives and a new voter coalition Mr. Poilievre is hoping to attract to the Conservative movement, the “Left Behinds.” Left Behinds feel they are falling further and further behind financially, do not trust the government, and are becoming suspicious of institutions. Trump has significant influence over both American and Canadian Left Behinds, and these voters will expect federal Conservatives to voice public support for Donald Trump, as well as Trump's politically damaging policies that repel centrist voters.Can Poilievre speak to the Left Behinds without alienating more moderate voters? Speaking to multiple audiences with perfect message synergy and zero contradictions is one of the most difficult tasks in politics. It requires message discipline, attention to detail, and mastery of digital media.The final challenge for Conservatives is that Trump will be a massive destabilizing opportunity for the Liberals in advance of the next federal election. The Liberal Party of Canada and Justin Trudeau excel at downloading U.S. issues into the Canadian political discourse, especially when it comes to policy issues that reflect voter values. Think, for example, abortion, firearms control, and political extremism. The Liberals will be quick to draw comparisons between Pierre Poilievre and Donald Trump on policy, tone, and values.On the issue of abortion, Donald Trump is widely viewed as being responsible for the U.S. Supreme Court overturning Roe v. Wade due to his judicial appointments to the upper court. The Democrats were then able to capitalize on the issue of abortion to defeat Trump-backed candidates during the U.S. midterm elections. Expect the Liberals to create a similar conflict point ahead of the next federal election by passing a law that will guarantee access to abortion. The Liberals will then warn voters that if the Conservatives form government, Poilievre will be forced by his caucus to infringe on a woman's right to choose by rescinding this newly created law. This is a daunting prospect for Poilievre and his team, because typically when elections are fought over values and not issues, Conservatives tend to lose.Of course, if Trump loses the Republican Party nomination, the Trump impact on federal Conservatives will only be short-term. I must think that's the scenario Mr. Poilievre and his senior team are cheering for. But until we know the outcome of the Republican presidential nomination, Donald Trump will continue to be a political nightmare for federal Conservatives.Jake Enwright is the Vice-President of Public Affairs and Communications for Syntax Strategic. He is a former senior adviser to previous Conservative leaders.