What does “breathe down one’s neck” mean?

Question

There was an article titled “Obama or Emanuel pushed to spotlight Solyndra” in today’s Washington Post, reporting that President Obama or his chief of staff were eager to help spotlight a solar company, Solindra. Eventually, the Department of Energy allowed (or was forced to allow) to pour $535 million in loans to the now shuttered company.

In the article, there was a sentence:

“Any word from OMB?” Department of Energy stimulus adviser Steve Spinner wrote to a department staffer about final terms of the Solyndra loan to be approved by the Office of Management and Budget. “I have the OVP and WH breathing down my neck on this.”

What does “breathe down one’s neck” mean?

Additionally, there was the line;

“Ron said this morning that the POTUS definitely wants to do this,” one White House staffer told an Obama scheduler on Aug. 17, 2009.”

What does “scheduler” mean?

Cambridge Dictionary online defines “scheduler” as “a person who works for a broadcasting company putting the various programmes for the day, week, month, etc. into a particular order.

But I don't think this applies to "Obama scheduler." What is Obama schedulers' job?

Answer 1

From the first Google result:

Idioms: breathe down (someone's) neck 1. To threaten by proximity, especially by pursuing closely. 2. To watch or monitor closely, often annoyingly: The boss was breathing down my neck all morning.

From the first Google result for Obama scheduler:

The Busy Life of Obama Scheduler Alyssa Mastromonaco
...
In her new role [as director of scheduling and advance], Mastromonaco will execute elaborate protocols that have been in place for decades, and her immediate staff of about 35 will include a "diarist," responsible for recording every one of Obama's moves -- the telephone calls, the meals, the basketball games. Each step in the White House scheduling process, from request to approval, must be documented in writing. Decisions are made by committee -- a very large committee of administrative heavyweights from the national security and domestic policy offices, speechwriting, catering, the first lady's and vice president's shops, the Secret Service and so on. Advance teams involve casts of hundreds, swarming into each of the locales, here and abroad, that a president will visit.