WASHINGTON—Senate Republicans blocked a bill that would provide legal protections for fertility treatments and mandate insurance coverage, despite GOP presidential nominee Donald Trump’s recent pledge to force insurance companies or the government to pay for them.

The US Senate is expected to hold a vote on Tuesday on a bill that would guarantee access to in vitro fertilization nationwide –- a move that comes as Democrats seek to pressure Republicans over the issue in the run-up to the November elections.

Republicans have blocked for a second time this year legislation to establish a nationwide right to in vitro fertilization, arguing that the vote is an election-year stunt after Democrats forced a vote on the issue.