Donald Trump is facing words of caution from within his party as the presumptive Republican presidential nominee narrows down his choice for vice president.

With former GOP presidential rival Nikki Haley continuing to chip away at his primary victory margins despite dropping out of the race two months ago, some Republicans are sounding the alarm for Trump to give more consideration to a vice presidential pick who can help close the gap with irritated supporters of the ex-South Carolina governor.

The latest warning sign for Trump came this week when roughly 1 in 5 — nearly 22% — of GOP voters in Indiana’s primary voted for Haley.

“There’s still a very sizable portion of the Republican Party that’s insisting on a candidate who they can be proud of, on account of their character attributes and who promotes a policy agenda consistent with basic Reagan-era principles,” Sen. Todd Young (R-IN), former chairman of Senate Republicans’ campaign arm, told the Washington Examiner.