As General Motors scrambles to figure out how to pay down $1.5 billion in debt due June 1 — the same day Uncle Sam is demanding the hobbled automaker present a new restructuring plan — the investors holding that debt are starting to splinter into factions.

According to sources familiar with the matter, some debtholders, including Sequoia Capital have stepped up efforts to ensure they get paid, but are complaining that they’re on the pay-no-mind list at GM.

Meanwhile, another group of bondholders that includes big institutional investors like Pacific Investment Management Co. and Fidelity Investments are sitting on the sidelines and are being looked at as holding off on taking any action in order to protect their relationship with the auto pensions, which are huge clients in those firms.

GM is racing to restructure a $28 billion debt load into equity in a newer, smaller company, and is expected to unveil a formal offer to its creditors next week.

However, debtholders like Sequoia fret they will get next to nothing of the company goes into bankruptcy, which is widely seen as the likely outcome given GM has had a tough time so far reaching its cost-cutting goals and just last week asked the government for another $5 billion on top of the $13 billion it has already received.

Since late March, President Barack Obama’s automotive task force has been driving GM to try to restructure its debt out of court and avoid a messy bankruptcy. GM may look to make a formal offer to creditors next week on such a conversion.

Sequoia, Pimco and Fidelity are among a group that owns $1.5 billion in Series D notes, which is debt that converts into GM common stock. However, the convertibles are essentially worthless given GM’s share price. Sequoia owns the biggest slug of this debt, at $400 million.

The stock closed at $1.66 yesterday, down 20 cents.

The lion’s share of GM’s obligations are related to claims from its unions. The company is trying to slash $10.2 billion from $20.4 billion in pension obligations, and bring its bond debt to less than $9.2 billion from $27.5 billion.

One of the many strategies being bandied about by the Obama administration is putting the company through a fast-track bankruptcy that would see it divided into a “good” company with assets GM wants to keep, and a “bad” company consisting of brands it wants to dump.

GM’s new CEO Fritz Henderson has embarked on a much more rapid scaling down of the company, and yesterday laid off 1,600 salaried workers. mark.decambre@nypost.com