Senate Republicans can't force the President to change foreign policy. All they can do is approve funding and that's it.
Trump wanted to pull The US out of NATO,the powers that be wouldn't let him.They wont let him pull out of Ukraine.
US is not in Ukraine, US is only sending weapons to Ukraine which is the sole authority of the President. Trump had stalled sending weapons to Ukraine even before the war and knowing that Trump is completely pro-Putin, it doesn't take a genius to figure out that Trump will end support for Ukraine.
Whoever the next president is they will not stop supporting Ukraine until Russia leaves.That is my opinion.
Current and former officials who were privy to the decision in December 2017 to provide the missiles to Ukraine told Foreign Policy that Trump had been reluctant to go ahead with the move and only did so when aides persuaded him that it could be good for U.S. business. “He wanted to know if the Ukrainians would pay us back,” said a former senior official with direct knowledge of the decision to provide Ukraine with a grant to buy the powerful anti-tank Javelin missiles. https://foreignpolicy.com/2019/11/15/trump-resisted-ukraine-sale-javelin-antitank-missile/
Your opinion.JFK was days away from bombing Cuba even though he didn't want to.The US is at war with Russia,the powers that be will not let Trump surrender just as they wouldn't let him pull out of NATO.
He doesn't have to surrender, he just have to delay sending weapons - something he has done in the past and it will be over within weeks.