The rising budget deficit will only become a problem

if the non-government sector eventually stops buying the debt that the Government is issuing.
if it exceeds the non-government sector's nominal desire to save in the currency of issue.
it will never be a problem because the national government is sovereign in its own currency.

Answer: if it exceeds the non-government sector's nominal desire to save in the currency of issue.

Please see Size of Deficit 101 for further details or post a question via the Comments.