The issue never seems to be directly addressed in the books, but in tGoF Voldemort mentions one of his motivations for a public duel with Harry being an intent to show that the "Boy who Lived" was simply lucky and did not provide any substantial opposition to their path to power.
However, in the graveyard Harry resists the Imperius Curse, dodges several of Voldemort's spells, wins a battle of wands, and successfully escapes with a whole horde of the top Death Eaters present.
Voldemort spends time in the next year trying to pull Harry into a trap in the Ministry which requires at least some Death Eaters to be constantly on standby, and despite eventually falling for the trap (months of effort), Voldemort does not obtain his ultimate goal, fails to kill Harry again despite arriving in person, and even exposes himself to the Ministry.
In the Battle of the Seven Potters Harry manages to ward off Voldemort once again due to some wand-lore, but it appears as a bit of particularly powerful magic to outside observers such as Hagrid.
That isn't even mentioning all of Harry's other small victories that might have gotten notice (e.g. gobbing Gringotts and escaping on a dragon). As readers we know that a lot of what Harry does has special circumstance behind it, but to a group of outside observers it seems like elevating him to mythic status could be very possible.
So is there evidence that the Death Eaters have some doubts when it comes to Voldemort's constant attempts to be dismissive of Harry's prowess? Is it possible Harry Potter is seen as an up-and-coming Dumbledore replacement?