What is the reason behind certain Republicans' opposition to providing additional assistance to Ukraine?

US aid to Ukraine has come to a halt due to mounting opposition from Republicans, despite warnings from the White House and Kyiv. Some Republicans insist that continued aid should be tied to US immigration and asylum reforms. Others oppose further aid to Ukraine on ideological grounds. Without their support, US assistance to Ukraine may run out by the end of the year. Republicans recently blocked a vote to advance a national security bill that includes funding for Ukraine. Democrats are pessimistic about the situation, as Republicans seem to be taking a hard stance on the issue. Some Republicans, like Mitch McConnell and Lindsey Graham, who are supportive of Ukraine aid, want to use it as an opportunity to achieve other policy goals such as tougher border security and immigration measures. They are open to negotiations and compromise. On the other hand, a small but vocal minority of Republicans, including Matt Gaetz, Jim Jordan, and Marjorie Taylor Greene, oppose Ukraine aid on principle, arguing that it is misguided or wrong. This isolationist wing of the party appears to be motivated by Donald Trump's opposition to aid for Ukraine. Overall, support for Ukraine is declining among Republicans, and tying the issue to border security can give Republicans a political advantage.