Find longest ordered substring in Python

index.py

longestOrderedPart 		= ''
randomString 			= 'ljdflkjdfabcdljfbcdxyzlsjmlkjqsmfslkjfqllldflsdlfsldmlsqmslfdk'
orderedPart				= randomString[0]

# loop over randomString 
for i in range(0, len(randomString) -1): #don't run over last character or nextCharacter will go outside of the bounds of the string
	currentCharacter = randomString[i]
	nextCharacter = randomString[i+1]
	
	#if nextCharacter is bigger or equal than currentCharacter, than it was in correct order 
	#in that case add character to orderedPart
	if nextCharacter >= currentCharacter:
		orderedPart += nextCharacter
		
	#else reset the orderedPart
	else:
		count = 0
		orderedPart = nextCharacter
		
		
	#if the temporary orderedPart is longer than the longestOrderedPart, set the new orderedPart to the longestOrderedPart
	if len(orderedPart) > len(longestOrderedPart):
		longestOrderedPart = orderedPart
	
#print out the longestOrderedPart

print(longestOrderedPart)