The Speaker of the House, at present Mike Johnson, is where the buck stops with trying to get the Continuing Resolution (this is the stopgap funding bill to avert a government shutdown, usually abbreviated in this context to CR) passed.
Johnson, though, has a wafer-thin majority of Republicans in the House. And many Republicans want the CR to include measures to curtail government debt, instead of it growing at a breakneck pace. Hence, their support is wavering.
Trump has been enlisted in efforts to put the pressure on to support the debt-growth bill. Government funding runs out on March 14. The pressure is indeed on.