I need some help in setting the correct pattern for grep. I need to find all occurrences of `pattern` where line *may have* leading space(s). For example: In the following file:

```
 1. No pattern recognized.
 2. Pattern to be recognized
 3.          Pattern to be recognized here also
 4.  pattern with only one leading space 

```

I would like to grep only lines 2,3 and 4. The line numbers are just for the reference.

So far I have tried the following: 

`grep -i '^ [[:blank:]]pattern'`, but it returns only line 4.

`grep -i '[[:blank:]]pattern'` returns 1,3 and 4.

`grep -i '^[[:blank:]]pattern'` returns 1,3 and 4.

-- Mike
P.S.
If this is not the appropriate forum, then please guide me accordingly.