There have been Republican elected representatives who have confronted Trump. With very few exceptions, they have gone down to defeat in subsequent Republican primary elections.
The Republican electorate will not stand for Trump being constrained or criticized by Republicans. That's why there are almost no remaining Republican elected officials who are willing to confront the Trump administration aside from a handful of lame ducks like Tillis and Massie.
Functionally, the Republican congress is unable to hold the Trump administration to account, because Republican voters have ensured that it cannot. The only way Trump will ever be constrained is via Democrats.