By Nick Assinder BBC News Online political correspondent

Is it too far-fetched to imagine that Gordon Brown's bedtime prayer is to ask his maker to guarantee Stephen Byers a long career in the cabinet?

For, every time the transport secretary is publicly branded a liar, Tony Blair's popularity slides and the chancellor's skyrockets.

Byers hitting Blair

Mr Brown now stands head and shoulders above all other ministers, including the prime minister, in voters' esteem.

Tony Blair must have known he was taking a risk when he so willingly backed his disaster-ridden secretary of state.

And it was always possible, if a bit surprising, that Mr Brown would benefit from his tax raising budget.

Dirty work

But Mr Blair's dogged support for "Liar Byers", as he is now almost universally dubbed, has clearly given the chancellor's popularity an added boost.

Mr Byers is one of Tony's oldest cronies, of course, and has done a lot of the government's dirty work - particularly over Railtrack.

And the prime minister clearly believes there is a media witchhunt to get Byers out - enough on its own to stiffen the prime minister's resolve.

Not always loved

But he is paying the price for his loyalty while Mr Brown, who has made no comments about Mr Byers, is reaping the rewards.

The transport secretary is now one of the most unpopular ministers in recent times.

According to a recent opinion poll he is even less loved than Margaret Thatcher was before the Falklands war salvaged her standing.

As unemployment rocketed those were the days she was still remembered as "milk snatcher", before she became the Iron Lady.

Lost votes

He is not unique in being the minister everyone loves to hate. There have been plenty before him.

So-called Prince of Darkness Peter Mandelson leaps to mind, as does former Tory minister Kenneth Baker, savagely depicted as a slug by the satirical puppet show Spitting Image.

Blair stands by his man

And it used to be said that whenever former home secretary Michael "something of the night" Howard appeared on television he lost the Tories thousands of votes.

>Even former Labour leader Neil Kinnock has been ready to admit he had a problem in winning over voters to his personality.

But few have managed to plumb the depths to the extent Mr Byers is currently managing.

Brave minister

It is one thing being branded slimy, likened to Dracula, or dubbed a Welsh windbag.

It is something quite different when, day after day, you awake to fresh headlines casually referring to you as "Liar Byers".

There is much speculation that the prime minister likes having Mr Byers around to continue doing his dirty work.

But, if that is the case, it is badly backfiring.

Mr Blair may have already decided to dump Mr Byers in the next reshuffle, assuming he can find anyone brave enough to take over the transport brief.

Gordon Brown will probably be praying he can't.