While Democrats still have over 20 major candidates competing for their party's nomination, the small 2020 GOP field has not created any concerns for the re-election campaign of President Donald Trump, as a former Tea Party Congressman announced this weekend he would take on Trump for the GOP nomination. 'He must not be re-elected,' Tea Party lawmakers turned conservative radio talk show host Joe Walsh wrote on Twitter Sunday night about President Trump. But a quick look back at Walsh's time in Congress, his attacks on President Barack Obama, and his recent change to hard-line Trump opponent didn't exactly leave political experts feeling like this was the start of something bad for Mr. Trump. On the ABC News program, 'This Week,' Walsh acknowledged that he was at the tip of the spear for Republicans in terms of pushing the party more and more to the right - creating an opening for President Trump. Also challenging the President is a former Governor of Massachusetts, William Weld - the Vice Presidential nominee of the Libertarian Party in 2016 - who has not moved the political meter against Mr. Trump. If one is looking to compare Weld, Walsh and any other GOP candidates, for a similar historical moment in modern Presidential politics, maybe you could look at 1968 when challenges built against President Lyndon B. Johnson, or in 1980, when Ted Kennedy took on President Jimmy Carter. But the difference is obvious right away - Walsh and Weld are not big names right now. Eugene McCarthy and Robert Kennedy were big names taking on LBJ. Ted Kennedy damaged Carter so much that it made Ronald Reagan's campaign that much easier. While President Trump has very strong approval ratings from Republican voters, his policies have certainly caused concerns among some in the GOP - like on tariffs - where President Trump has suddenly turned the party of free trade into the party of protectionism. 'The tariffs are attacks on the American people,' said ex-Rep. Dave McIntosh (R-IN), who now heads the conservative group Club for Growth, though McIntosh made clear he wasn't going to abandoning the President any time soon. Business groups - once a super reliable source of support for the GOP - are also increasingly going public with their concerns about the President's extra tariffs on China. 'Tariffs hurt retail,' said Matthew Shay, the head of the National Retail Federation. 'It's impossible for businesses to plan for the future in this type of environment,' the group said over the weekend. Other groups like the U.S. Chamber of Commerce fully support more aggressive American treatment of unfair trade practices by the Chinese - but they are worried the President's tariffs aren't the right answer. 'While we share the President’s frustration, we believe that continued, constructive engagement is the right way forward,' the U.S. Chamber of Commerce said in a statement. But there's certainly been no rush to throw Mr. Trump overboard, no matter the policy differences.