Sen. Claire McCaskill (D-MO), for the fourth consecutive month, ranks as the most unpopular U.S. senator up for re-election, according to a poll released last week.

Forty-six percent of Missourians disapprove of Sen. McCaskill, while only 38 percent of Missouri citizens approve of the Missouri Democrat, according to a Morning Consult poll. Among senators up for re-election, Sen. McCaskill has ranked the least popular for the fourth month in a row.

Fifty-three percent of Missourians believe it is time for a new Missouri senator, compared to just 31 percent of Missourians who believe Sen. McCaskill deserves re-election.

An NBC News/Marist poll released last week showed that the race between McCaskill and her Republican challenger, Missouri state Attorney General Josh Hawley, is now tied for the Senate race. The survey found that both contenders receive 47 percent of the vote.

Kelli Ford, a spokesman for the Hawley campaign, said in a statement on Monday:

Claire McCaskill and her dark money allies have spent millions of dollars in Missouri this year with little to show for it. She consistently votes against Missouri when it matters – from opposing middle-class tax cuts, to being wrong on the last five Supreme Court justices, to voting against the border wall. Washington is broken because of career politicians like Claire McCaskill, so it makes sense she’s the most unpopular and people want someone new.

Scandals have rocked Sen. McCaskill’s re-election campaign. A report released in July revealed that businesses with ties to McCaskill’s husband, Joseph Shepard, received $131 million in federal government subsidies since her election to the Senate in 2007.

McCaskill faces an increasingly competitive Senate race in a state Donald Trump won in the 2016 presidential election by 18.5 percent. The tight election between Hawley and McCaskill has continued to put pressure on the Missouri Democrat to back Trump’s Supreme Court nominee, Judge Brett Kavanaugh.